We are sorry to have to record the death of Sally Clark, who died aged 42 on 16 March 2007. The cause of her death is not yet known. She suffered the most severe effects of being wrongly convicted of the murder of two of her children. We hold the people and organisations who accused and convicted her responsible for her untimely death. They convicted her on no evidence, but rather because they could not admit to their own ignorance of the cause of death of the two babies, and so blamed her instead.

Angela Cannings, who spent 18 months in prison after a wrongful conviction for killing her own two babies, said last night: "I'm really speechless, I'm so angry. This lady suffered so much - now she's died, I'm just shocked and stunned."

Penny Mellor, a friend of the Clark family, said that Mrs Clark's time in prison had left a stain on the rest of her life. She was assaulted by other prisoners and lived in fear that they would try to poison her food. 'If you've been convicted as a child killer you become a focal point for all the hatred in prison,' she said.

Read more at :
Sally Clark was 'let down' by authorities, by Jamie Doward, 18 March 2007

Expert Professor Sir Roy Meadow struck off medical register by BMC - BBC News 15 July 2005

Stolen Innocence by John Batt - a comprehensive account of this case by a solicitor and writer who is also a family friend

Articles reprinted here:
The case was also featured on Radio 4's Woman's Hour in July 2001. The program looks at the campaign and the medical evidence and may be heard on the Internet (click here for netcast), courtesy of the BBC's Listen Again service.

'Sally Clark trial pathologist guilty of incompetence' - The Times 28th May 2005
'Mother accused of killing sons cleared by appeal court' - Guardian, 30 January 2003
Tests 'show mother did not kill sons' - Guardian, 3 July 2002
'New facts raise more doubt'- Independent, 2 July 2002
'Lawyer in jail for murder has hope of appeal' - The Times, 17 June 2002
'I am afraid Sally is giving up hope in prison' - Sunday Times, 20 Jan. 2002
'There's not an ounce of violence in Sally' - The Times, 23 Oct. 2001
'Gene find casts doubt on double 'cot death' murders' - Guardian, 15 July 2001
'Conviction by mathematical error?' - British Medical Journal
'Lawyer loses baby killing appeal' - BBC News, 2 Oct 2000
Stephen Clark, Sally's husband, makes an impassioned plea on her behalf - The Times, 8 Oct 2000
'Mother who murdered baby sons loses appeal' - Guardian, 3 Oct 2000
'Solicitor did kill baby sons, rules Court of Appeal' - Independent, 3 Oct 2000

See also:
Sally Clark website
with an excellent article, 'Against The Odds', by Bob Woffinden writing in the Sunday Telegraph

A Home office pathologist was found guilty yesterday of incompetence in conducting post-mortem examinations that led to Sally Clark being wrongly jailed for the murder of her two babies.

Alan Williams, who had said that there was overwhelming evidence of a double child murder, faces being found guilty of serious professional misconduct. The General Medical Council make a determination on that point next week.
Dr Williams, 58, is alleged to have botched post-mortem examinations on 12-week-old Christopher Clark, in 1996, and his 8-week-old brother, Harry, two years later.

30 January 2003

Mother accused of killing sons
cleared by appeal court

By Tania Branigan

Sally Clark, the solicitor jailed for life for murdering her two baby sons, walked free from the court of appeal in London yesterday after three judges quashed her convictions.

They ruled the convictions were unsafe as medical evidence that might have cleared her was kept secret during her trial.

They also criticised the use in the trial of a statistic putting the chance of two babies in the same family suffering cot death at one in 73 million as "grossly misleading".

Mrs Clark, 38, had served three years of a life sentence following her conviction in 1999 for smothering 11-week-old Christopher in 1996 and shaking eight-week-old Harry to death two years later. She has always maintained that they died of cot death syndrome.

But Mrs Clark, whose husband Stephen has always insisted that she was innocent, said that the decision was "not a victory".

"There are no winners here. We have all lost out," she said as she left court. "We simply feel relief that our nightmare is at an end. We are now back in the position we should have been in all along and plead that we may now be allowed some privacy to grieve for our little boys in peace and try to make sense of what has happened to us."

The judges at her first appeal in 2000 described the evidence against her as "overwhelming" despite accepting that the one in 73 million figure was wrong.

But last year the criminal cases review commission, which reviews potential miscarriages of justice, referred the case back to the appeal court after it emerged there was clear evidence of an infection that had spread as far as Harry's cerebral spinal fluid.

Mrs Clark was arrested after Harry's death, as experts had assumed Christopher died of natural causes.

Clare Montgomery QC, acting for Mrs Clark, had told the court that Mrs Clark and her advisers had believed there was no evidence of infection.

In fact, it appeared that the evidence had been known to prosecution pathologist Alan Williams - but not to other medical witnesses, police or lawyers - since February 1998.

Lord Justice Kay, sitting with Mr Justice Holland and Mrs Justice Hallett, ruled that Mrs Clark's trial had not been fair because the jury were unable to hear medical evidence that might have influenced them.

"This resulted from the failure of the pathologist to share with other doctors investigating the cause of death information that a competent pathologist ought to have appreciated needed to be assessed before any conclusion was reached," they said.

They stressed that they were not suggesting Dr Williams had acted deliberately.

Lord Justice Kay added that the one in 73 million statistic was "grossly misleading", because the jury started from the incorrect assumption that dual cot deaths in a single family were extremely rare. Experts now believe the risk could be anywhere between one in 100 and one in 8,500.

He added: "This is not like other cases where there is clear evidence of baby shaking or striking."

Mrs Clark appeared tearful as she emerged from the cells and shared a long embrace with her husband Stephen.

Thanking her family, friends and legal team for their "unwavering and unconditional support", she said that the couple hoped for privacy to rebuild family life with their four-year-old son.

The prosecution said it would not ask for a retrial because additional medical tests which would be pertinent could no longer be carried out and because there had been so much publicity that a fair trial would be impossible.

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The case of Sally Clark - convicted of murdering her two sons - has been one of the most controversial in modern criminal history. However, newly disclosed results of microbiology tests carried out on her second child, the eight-week-old Harry, indicate he died of natural causes.

This crucial information was not disclosed at her trial. Clark's family and lawyers say the jury were left with the impression that hospital tests had excluded all possibility of death from natural causes.

Clark, now 37, has protested her innocence throughout. Christopher died aged 12 weeks in the evening of December 13, 1996, while she was at home alone with him, after she had put him in a Moses basket.

Harry was born on November 29, 1997. Although the family took many precautions, like using an apnoea monitor, the baby died in his bouncy chair on the evening of January 26, 1998. In July of that year, Clark was charged with the murders of both children, and she was convicted the following year.

A key defence witness at the trial, Tim David, professor of child health and paediatrics at the University of Manchester, analysed blood tests carried out on Christopher. He concluded that the child could have died of a rare lung disease, idiopathic pulmonary haemosiderosis.

During Professor David's evidence in chief, and again during cross-examination, the jury passed notes to the judge asking if blood tests had also been carried out on Harry. The prosecution told the jury: "A sample was not collected from Harry to analyse sodium in his blood".

The Clark family, like the jury, were left with the impression that no tests had been done on Harry. However, Sally's husband Steve spent two years trying to get all medical records relating to the deaths of his children from Macclesfield hospital. Finally, in April, to his astonishment, he was sent a vast number of documents, among which was a copy of a previously undisclosed microbiology report.

It now seemed that Alan Williams, the pathologist who carried out the postmortems, had carried out tests.

"When the post-mortem was carried out," explained John Batt, a friend of the Clarks who is also a solicitor, "Dr Williams took cultures from the stomach wall, both bronchi, both lungs, the trachea, the throat, and, most importantly, the cerebro-spinal fluid. He sent the cultures to the lab for microbiology tests. The results were available within 48 hours. Staphylococcus aureus was present in all of the sites."

Such results can sometimes be misleading, as it is difficult to avoid contamination at autopsy and the infection could have arisen after death. So in order to obtain an expert opinion on the significance of this finding, the newly revealed report was sent to consultant pathologist James Morris, honorary professor of biological sciences at the University of Lancaster and one of the country's leading experts in bacterial toxins in cot death cases.

Having read the evidence, he concluded that the possibility of infection arising after death could be excluded. "Cerebrospinal fluid (CSF) is normally sterile," he wrote. "The presence of a pathogen is therefore highly significant. There is no evidence that staphylococcal organisms could get into the CSF after death. The fluid contained a number of polymorphs [white blood cells], showing there had been a reaction to the organism and therefore that it was present prior to death."

Professor Morris noted that "overwhelming staphylococcal infection... is a very serious and potentially lethal disease. It can progress so quickly that death occurs suddenly without obvious pre-existing illness. It is a recognised cause of sudden and unexpected death in infancy. This is natural disease." On the basis of the evidence now available, he reported that this was the the most likely explanation of Harry's death. He emphasised that "no other conclusion could be sustained."

The Clark family sent the new material to Glyn Walters, a retired consultant in chemical pathology. He, too, concluded that Harry's death was due to "a disseminated staphylococcal infection". In fact, in his post-mortem report on Harry, Dr Williams categorically stated: "There is no evidence of acute infection... there is no evidence that this child died as a result of natural disease." In the light of the new material, this is now in doubt.

"The jury were aware Dr Williams's findings were the subject of much criticism," said Michael Mackey, Clark's lawyer. "They never knew he had commissioned tests which showed, at the least, a potential natural cause of death to which he made no reference [in his evidence]. How would that knowledge have affected their view of his competence?"

Leading paediatrician Sir Roy Meadow told the jury there was a one in 73 million chance of two cot deaths occurring naturally in the same family - something he estimated would happen less than once a century. In fact, actual incidence of a second cot death, as others have since pointed out, could be as low as 1 in 64.

The referral of the case to the criminal cases review commission will give renewed hope to mothers convicted of murdering their children in similar circumstances, who have protested their innocence.

These cases include those of Maxine Leggatt, whose two children died in their beds on the same evening near Chester-le-Street, Co Durham, and of Angela Cannings, convicted in Winchester in April of murdering two of her children.

Steve Clark last night acknowledged these other cases: "Others in this situation do not have the resources or support we have been so fortunate to enjoy. But it is frightening to think we might never have discovered those test results."

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Strong evidence that may point to the innocence of Sally Clark, the solicitor serving a life sentence for killing her babies, was not disclosed in court during her infamous "73 million to one" double murder trial.

The development highlights growing fears of a reversal of the presumption of innocence – a cornerstone of the English legal system – in cases where mothers are accused of killing their babies.

Clark's husband, Steve, said: "We have discovered new medical evidence which wasn't disclosed to the defence at the time of the trial which appears to reveal a natural cause of death for one of our babies."

Tests were carried out on the blood and tissue of the second baby to die, Harry, on samples taken by a Home Office pathologist, Dr Alan Williams. The report containing the results – compiled in January 1998, a few days after Harry died – was not used in the trial, held in October 1999.

Mr Clark tells BBC Radio 4's File on Four programme, to be broadcast tonight: "We found about it almost by accident really, hidden away in a huge pile of papers that we finally managed to extract from Macclesfield Hospital late last year after almost two years of asking for them, and the scary thing is that it could still be there and no one would know."

The report is believed to provide compelling evidence that Harry died a natural death. If the conviction for Harry's murder was undermined, it would automatically raise doubts about Clark's conviction for the murder of her first son, Christopher.

The Criminal Cases Review Commission is looking at the case, and the Clark family expects it to be returned to the Court of Appeal.

Mr Clark remains astonished that the crucial material was not seen by the defence: "The report was not disclosed to the defence at the time of the trial, even when the jury asked a specific question about that area," he said.

At Clark's trial in October 1999 the results of the tests Dr Williams commissioned on baby Harry were not disclosed to the court.

Mr Clark said: "When I saw the report I didn't know what its significance was, but we passed it to some of the doctors who have been helping us behind the scenes and they almost said 'eureka!'. We now have statements from two eminent British pathologists in this field, stating that the second baby died from natural causes.

"I have always known that my wife was innocent and have been determined to find justice for her. After more than four years of struggle, I hope that the system will now move quickly to give it to us.

"Sally's first reaction, when I told her, was not 'thank goodness, I'm coming home', but to burst into tears and then ask, 'Harry didn't suffer, did he?'. As is so typical of the kindest and gentlest person I have ever known, her first thought was not for herself, but for her baby.

"We still have not been able to grieve properly for our little boys, and should never have been put in this appalling situation where it is we who have had to find out the true cause of death."

Mr Clark added that Dr Williams should not have been relied upon because he was not a paediatric pathologist and he pointed out that the prosecution admitted a fundamental error was made by both Dr Williams and another pathologist in one of the post-mortem examinations. In addition, Dr Williams was found to have made mistakes in another case.

The vital question now is why evidence that suggested Clark was innocent was never put to the jury. Dr Williams has declined to comment.

Professor Sir Roy Meadow, the star witness for the prosecution, testified that the two deaths were unnatural. He told the jury that there was a "one in 73 million chance" that both deaths had occurred naturally.

Sir Roy added that there were specific features in the case which made the likelihood of innocent death even more remote, saying "it could only happen once every 100 years".

The "73 million to one" figure was a statistical smoking gun. In one soundbite the jury had a compelling case against Sally Clark. The jury, some of whom were openly weeping, convicted her by a majority of 10-2, after two days of deliberations.

But the statistic was grossly inaccurate. It is more, rather than less, likely that a mother who has suffered one cot death will suffer another. The true odds were not one in 73 million but one in 60.

Despite that, the Court of Appeal ruled that the mistake did not have a significant impact on the jury's decision.

The campaign to establish Clark's innocence was bolstered when the Solicitors' Disciplinary Tribunal made the unprecedented decision not to strike her off the Law Society roll, signalling that many in the legal world were not convinced of the safety of her conviction.

For that tribunal she had prepared a video, in which she said of her ordeal: "I now suffer the minute-by-minute torture of life imprisonment, knowing, as I accept only I could know, that I did not harm my little boys and did nothing but love them."

Had the jury known about the test results that suggested Harry died of natural causes, they might not have convicted her. Other prisoners are notoriously cruel to child killers, and Mrs Clark suffered threats and some violence when she was first locked up at Styal prison near Manchester.

Mr Clark said: "It is virtually impossible for innocent mothers who have endured cot deaths to defend themselves from the charge of murder.

"The first question to my wife by the prosecution at the trial was: 'You were never cut out to be a mother, were you?' The burden of proof has been reversed in these cases. Mothers who have suffered cot death are assumed to be guilty until they can prove they are innocent.

"It has taken us, with all our resources and support, nearly three years to prove Sally's innocence; yet still she is in prison, separated from me and our surviving child, who badly needs his mummy."

There are also grave concerns about the safety of the conviction of Angela Cannings, who, like Sally Clark, was found guilty of double murder and sentenced to life imprisonment in April this year. Sir Roy Meadow's published view in such cases is that, unless proven otherwise, one cot death is a tragedy, two is suspicious and three should be seen as murder. Cannings suffered two cot deaths – and then her third baby died.

At her trial at Winchester Crown Court, one of the main prosecution witnesses, who told the jury that the deaths were not natural, was Sir Roy. Cannings continues to protest her innocence.

Terry Cannings, who, like Mr Clark, is convinced his wife is innocent, said: "Matthew was pronounced dead on 12 November 1999. The police officer knelt down, held Angela's hand and said: 'I'm sorry but I've got to arrest you on the suspicion of three deaths – Gemma, Jason and Matthew.' It was like she was shot in the kneecaps."

Dr David Drucker is a microbiologist at the University of Manchester. A colleague of his performed tests on Matthew's body, which showed that the baby's immune system was not working properly.

Dr Drucker said: "That baby had so few antibodies of an entire class of antibody that it was just about almost below the limit of detection of the tests that were being used. And I remember commenting to someone at the time if I'd had so little antibody, I would expect to be dead or very seriously ill.

"I wasn't a jury member, so I don't know what went through their heads, but I don't know how they could ignore a finding that was so important."

The latest discoveries in genetic science, Dr Drucker said, suggested that Sir Roy's view on multiple cot deaths does not make scientific sense.

With colleagues at Manchester University, he has discovered what they believe to be a "cot death gene". In layman's terms, the cot death gene is a faulty switch – it fails to switch on the baby's defence system against killer bugs. There is a gap between the mother's defence system fading out as the baby grows to around eight weeks old and the baby's own defences kicking in. And it is through that gap that a bug or infection can strike.

Sir Roy does not agree. "There is no evidence that cot deaths run in families, but there is plenty of evidence that child abuse does," he has said.

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Sally Clark, the solicitor who was convicted of murdering her two babies, is likely to have her case referred back to the Court of Appeal on the ground of new medical evidence.

Clark is serving a life sentence after being convicted of the murders of Christopher, aged 11 weeks, and Harry, eight weeks, crimes of which she insists she is innocent.

The Criminal Cases Review Commission, which handles alleged miscarriages of justice, has reviewed her case and is expected to refer it back to the Court of Appeal for a possible re-hearing. It is believed that the commission, whose final decision is expected within two weeks, has been swayed by medical evidence suggesting that Harry died of natural causes. There is already evidence that Christopher died of natural causes that was not considered at trial.

The commission's likely decision has been signalled by a move by the Office for the Supervision of Solicitors to defer its appeal over Clark's professional status.

Her case came before the Solicitors' Disciplinary Tribunal last May, but in an unprecedented move it did not strike her off the roll, instead suspending her indefinitely after hearing from her lawyer and watching a video statement by Clark
herself, made from Bullwood Hall prison. The tribunal ruled that as Clark was already in prison it did not need to consider the punitive element of any penalty or the need to protect the public.

Steve Clark, Sally's husband, who is a partner with a City law firm, would not comment on the latest developments in her case, saying only: "We are quietly hopeful."

A referral back to the Court of Appeal could result in a rehearing of Clark's appeal as early as October. Clark, 37, a corporate lawyer, was given two life sentences at Chester Crown Court in November 1999 but has always denied killing her two sons at the home she shared with Mr Clark in Wilmslow, Cheshire.

In a few days’ time David Blunkett, the home secretary, is expected to set a sentence tariff for Sally Clark, the solicitor jailed for the murder of her two sons when they were no more than a few weeks old, writes Margarette Driscoll.

Though the sentence set in court was mandatory - life - the home secretary has the discretion to vary the actual time served. He is currently mulling over a thick file of submissions from family, friends and expert witnesses.

Ever since the jury reached a majority verdict of guilty at Chester crown court in November 1999, there have been public and private misgivings about the case among lawyers, doctors and families who have suffered the tragedy of losing a child through cot death.

The Clarks have received hundreds of letters of support from the public, many of which are included in the Blunkett file. The unease in the legal profession was evident last year when a disciplinary panel of the Law Society decided to suspend Clark; a solicitor convicted of such a serious crime would normally be automatically struck off.

More than two years after the trial Sally Clark still vehemently protests her innocence, but having lost an appeal against conviction last October and spent her third Christmas in jail, she is downcast. “She told her father recently she felt numb; she couldn't even get angry any more," says her husband, Stephen. "I am afraid she is giving up hope."

The wheels of justice grind infuriatingly slowly. The Criminal Cases Review Commission is to look at Clark's case but she is at the back of a long queue of potential miscarriages of justice.

One encouraging sign is that the commission has ordered the Crown Prosecution Service to preserve tissue samples remaining from the babies' post-mortem examinations. The family hope they can be used for new tests, based on research into genetic factors in cot death completed since the trial, and other tests that might produce an explanation for the babies' deaths.

A new study by the Royal College of General Practitioners also shows an intriguing correlation between the babies' deaths and national incidence of lung infection. Christopher, Clark's first son, died just short of a five-year peak. Her second son Harry died at a lower peak, but one that the author of the study still regards as "statistically significant". Christopher was originally certified dead of a respiratory infection.

Meanwhile, Stephen, 40, juggles a new job with a London law firm with life as a single father to the couple's surviving son, who is now three. Every week he takes his son to visit Sally at Bullwood Hall prison in Essex. "When he goes in he runs to her. He sits on her knee and reads a book," says Stephen. "For his sake she's keeping herself going; he needs his mum. But it must kill her every time we leave."

His son talks about prison as "Mummy's house". "He's started asking why Mummy can't come to our house," says Stephen.

"It's getting to the stage where I am going to have to talk to him about all this and I haven't got a clue what I'm going to say."

Last year Stephen left his job in Manchester. Fighting the case and preparing the appeal had all but wiped them out. He estimates that the case has cost the couple £250,000 - "everything we worked for" - even though several legal and medical experts have given free advice.

The house and car had to be sold to pay legal fees and when he moved south, to be near Sally, it meant starting again. One consolation was being offered jobs by several City law firms. The fact that they were willing to take him on despite knowing about Sally was a welcome boost to morale.

Sally has never seen the house that he and his son live in now, but she helped choose it, poring over estate agents' details. Stephen took paint charts into prison so she could choose. They picked furniture together, from brochures.

Sally also chooses all her son's toys and clothes. "Some time soon we'll have to start thinking about schools so I'll be taking in Ofsted reports," says Stephen. "I want her to stay involved in every aspect of our lives. Our house is very much her house; it's got her stamp all over it. When she is released I want her to step into a life that she is familiar and comfortable with. Keeping a ‘normal' family life going despite everything is a way of fighting back."

Clark was convicted of murder without anyone being able to say definitively how either baby died. The prosecution maintained that both babies had sustained physical injuries, deliberately inflicted, even though none was apparent when they were admitted to hospital. The defence argued that the pathology that alleged such injuries was flawed and that any injuries that did exist were due to vigorous efforts at resuscitation.

There were nine days of complex and conflicting medical evidence, some of which even Stephen, an experienced lawyer, struggled to understand. But in just a few minutes' discussion of cot death Professor Roy Meadow, a world-renowned expert in child abuse, told the court that the chances of two such deaths occurring in a non-smoking, middle-class household such as the Clarks' was one in 73m. Clark's family, and other independent observers, believe the statistic - easily understood but wrong - sealed her fate.

The daughter of a senior police officer, Sally, 37, met Stephen, a corporate lawyer, when they both worked in the City. In 1993 they moved to Manchester, where they joined a leading law firm and bought Hope Cottage, a pretty, detached house in Wilmslow. It was there that Christopher died, in December 1996, aged 11 weeks.

Stephen was out for the evening. Sally went to make a cup of tea at 9.30 and says when she returned, Christopher had turned grey. A post-mortem examination concluded that he had died of a respiratory infection.

Just over a year later, in January 1998, tragedy struck again, at the same time of evening, when Sally was alone with eight-week-old Harry. Stephen was in the kitchen making a bottle for him when he heard Sally scream from upstairs. This time, the pathologist was suspicious. Two months later, Sally was charged with murder.

Last year a manslaughter trial in which a dentist and an anaesthetist were accused of killing a five-year-old girl collapsed when Alan Williams, a pathologist, admitted having made a mistake. Williams was the man who raised the alarm about Clark. Meadow recently acknowledged that crucial evidence given by him on whether one of the babies had been smothered was based on data his secretary had shredded.

Clark faces many years in jail but even some of those who believe her guilty doubt whether this is the right place for her. In three recent cases of infanticide, the mothers were not jailed.

Stephen refuses to entertain the possibility that she could have been involved. "Sally would never have harmed our babies," he says. "She loved them." He has a faint hope that if the home secretary is guided by the principles of deterrence and retribution he could conclude that both have been satisfied by "time served".

But experience tells him a happy outcome is unlikely. "I've lost my faith in the system," he says. "If this could happen to us, people with friends, a bit of money and intelligence, it could happen to anyone. At law school I used to wonder how anyone ever got a conviction, the standard of proof was so high. Now I know it's all a game about what's admissible as evidence. It's not about discovering the truth."

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Looking back, Steve Clark bitterly regrets waiving his right to a solicitor one Monday in February 1998. He and his wife Sally found themselves under arrest on suspicion of murdering their eight-week-old baby, Harry, just four weeks before. Still grieving from his death - the second baby they had lost - they were awoken by police.

“It was a dawn raid,” Clark recalls, “by plainclothes officers, on a Monday morning, when neither of us was dressed. We were taken to Wilmslow police station and held for ten hours, in cells, after giving all our property over - I had to take off my tie, my shoelaces - until they decided to talk to us." Both solicitors themselves, they had faith in the legal system. "We talked openly - we had nothing to hide - and waived our right to a solicitor. But things we said then, to be helpful, were later used against us by prosecuting counsel." It was the start of a legal nightmare. In July that year Clark's solicitor called him in to break the news that Sally was being charged with the murders both of Harry and their first son, Christopher, aged 11 weeks, in 1996. "A top QC had told us that there was no case to answer," he says. "But the local CPS knew better. I was frightened, shocked and very angry - there was no more evidence against Sally than against me. I felt sick in my stomach."

Sally, 39, was convicted at Chester Crown Court in November 1999, and jailed for life. Since then, Steve, 36, has campaigned tirelessly, insisting that she is the victim of a gross miscarriage of justice. Many friends in the legal profession - as well as strangers - have rallied round and there is mounting support for her release.

Now at a City law firm, Clark splits his time between building up his legal practice after a gap of 16 months, looking after the couple's third son, and working on Sally's case. His belief in her innocence has not wavered. "We've been married for more than 11 years and I know Sally better than anyone else. In all that time, I never saw her raise a finger to any person or thing. She's the gentlest, kindest person I've ever known . . . there's not an ounce of violence in her whole body."

Speaking for the first time at length about the case, he admits that over three years it has crossed his mind to ask himself if his wife could have killed their children. "I'd be lying if I said I had not considered it. But immediately I dismissed it. Sally was a kind, caring and loving mother - and that's not just my view, but one held by all the professionals who dealt with us, including our nanny, who was with us when Harry was born, and helped me since. It's inconceivable that she did anything to hurt her babies."

Clark is a banking and finance lawyer while Sally did corporate work. They met in London- he was with Clifford Chance, she with Citybank - and decided to move to Manchester "for a better lifestyle and raise a family". Both worked with Manchester law firms, Steve as a partner with Addleshaws, and his wife with Halliwell Landau, although they ended up together after his wife's department was wooed by Addleshaws. Their first son, Christopher, was born in 1996. "We had a nice house, good jobs, lots of friends, a loving family - our lives were almost complete. All we needed was to start a family. We were very, very happy."

Media reports depicted Sally as a career woman who resented the changes wrought by motherhood. Clark is dismissive: "What attractive, professional, slim woman who becomes pregnant does not have thoughts for a moment - do I want this? But when Christopher was born, she fell in love with him. The health visitor said they had a strong bond. You can tell from eye contact."

The Crown case was that Sally had smothered Christopher and shaken Harry to death. But the evidence was riven with inconsistencies. When one Crown witness changed his mind, removing "evidence" of Harry having been shaken, the prosecution changed tack.

It said the baby could have been smothered, even though at the committal hearing the Home Office pathologist, Dr Alan Williams, stated the opposite. Prosecution witnesses also disagreed over Christopher's death. But another witness, Sir Roy Meadow, an emeritus paediatrics professor, came up with the statistic that the chance of two cot deaths in one family was one in 73 million. The Royal Statistical Society this week will express concern about the use of such statistics. But it was thought crucial in influencing the jury. Now genetic research has shown that if a family suffers one cot death, the chances of a second are one in four.

Clark is angry about flaws in the evidence. Worse, an appeal failed; one barrister said Sally had been "cheated of her liberty". The Court of Appeal had accepted that the one in 73 statistic was wrong but concluded it was a "sideshow" and had not affected the jury verdict, even though it made tabloid headlines.

He hopes the Home Secretary will set a jail term as "time served", allowing for her immediate release. It is believed that the judicial recommendation stands at 14 years. At the same time, he is about to lodge an appeal with the Criminal Cases Review Commission on grounds of fresh medical evidence. The irony is that had Sally pleaded guilty to infanticide, she would have been put on probation. "But she rejected the idea of pleading guilty to something she did not do."

Even now, he says, his wife is quietly confident that justice will be done. "She was brought up with a highly developed respect for the law. She still thinks the system will see justice done and her innocence will prevail."

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Sally Clark was sent to prison two years ago, condemned to life inside for murdering her two babies because - among other evidence - there was only 'one chance in 73 million' of the babies, born a year apart, both dying of natural causes.

But the discovery of a cot death gene means that the odds for a second death could have been as high as one in four - and that by hearing 'one in 73 million' the jury was presented with a simple, but false, probability.

The new genetic research raises the possibility that Clark - and other women - have been the victims of an appalling series of miscarriages of justice in multiple cot death cases.

A joint investigation by BBC's Five Live Report and The Observer has revealed a climate of suspicion against mothers who suffer two or more cot deaths, based on the 'crude aphorism' of top paediatrician Professor Sir Roy Meadow that, unless proven otherwise, 'two is suspicious and three is murder'. Sometimes known as 'Meadow's Law', it has been adopted by doctors, lawyers and the police.

Manchester University's discovery of a cot death gene in February knocks flat the view of Meadow and others that one should 'think dirty' about multiple cot deaths.

Microbiologist Dr David Drucker, who helped to identify the cot death gene, said of Meadow's Law: 'It's scientifically illiterate.' His is not a lone voice.

Now Clark's defence team intends to prepare a fresh appeal, based in part on the discovery of the cot death gene. Other appeals are likely to follow.

Clark maintains her innocence: 'I now suffer the minute by minute torture of life imprisonment knowing, as I accept only I could know, that I did not harm my little boys, and did nothing but loved them.'

Clark's first child, Christopher, was born on 22 September 1996 and died 11 weeks later. At the time, he was certified to have died naturally from a lung infection. Her second child, Harry, was born on 29 November 1997, and died eight weeks later in January 1998.

The next month, Clark was arrested for murder. Still grieving, she was accused of smothering Christopher and shaking Harry to death. When she was found guilty in November 1999, newspapers ran claims that she was a binge-drinker - none of which was presented as evidence in the case.

The forensic evidence at the trial was complicated and difficult to deal with as the 'victims' were so young. The evidence was also disputed and the prosecution case hotly contested. But, as both babies had died in Sally Clark's care, the defence could only put up her word for it that the babies had died naturally.

Solicitor John Batt has known Clark since she was five: 'What I believe the jury's reaction was is: "If she can prove that she did nothing to her babies, we'll let her off. If she can't, she must be guilty." But there is no way that a mother or science can prove that she didn't smother or shake her babies.'

Like an arrow through the fog came the assertion by Meadow that there was only a 'one in 73 million' chance of a mother having two consecutive cot deaths - the likelihood of an such an event happening, he said, was once every 100 years.

Meadow is a knighted professor and, everyone agrees, a superb performer in the witness box. It was a statistical smoking gun. In one soundbite the jury had a compelling case against Clark. They convicted her 10-2.

Meadow was knighted for his services to the study of child abuse. He was the first President of the Royal College of Paediatrics and Child Health and developed a controversial theory regarding a new form of child abuse known as 'Munchausen's Syndrome By Proxy' where parents fabricate symptoms of illnesses in their children, subjecting them to unnecessary medical treatment, and, in some cases, inflict injuries on them or even kill them in the process. For example a mother who seeks attention by murdering her baby and passing off the killing as a cot death.

Now, some experts contest the theory's merit. In his book ABC of Child Abuse, Meadow writes: '"One sudden infant death is a tragedy, two is suspicious and three is murder until proved otherwise" is a crude aphorism but a sensible working rule for anyone encountering these tragedies.'

Meadow has given evidence for the prosecution in criminal trials and family courts around the world. Often, his evidence - with other testimony - leads to convictions and mothers losing their babies to care.

No one is suggesting mothers never kill their babies. But Meadow's Law risks tarring all mothers who have suffered multiple cot deaths as murderers. It presumes guilt, and the presumption kicks in at the moment a second cot death occurs - when an innocent mother would be going through unendurable pain.

Many at the trial believe Meadow's soundbite statistic damned Clark. It was worked out on the basis that there are eight cot deaths a week in Britain. Then family circumstances are factored in: a single parent smoker is more likely to suffer a cot death than a well-off family. The Clarks are solicitors and non-smokers.

When all these factors are taken into account, you arrive at a figure of one cot death in 8,543 in a well-off family like the Clarks.

As the Clarks suffered two deaths, Meadow multiplied 8,543 by 8,543 and arrived at the chance of one in 73 million for two babies dying of natural causes. He then specifically linked the statistic with Clark's case.

Not a single statistician we have contacted has said that 'one in 73 million' - and the way in which Meadow used it - is defensible.

Peter Donnelly, professor of statistical science at Oxford University, is scathing: 'It is poor science. It's not rigorous, it's just wrong.'

Dr Stephen Watkins, Stockport's director of public health, said: 'This is a breach of a fundamental axiom of probability theory... the equivalent of two plus two equals five.'

Watkins was so troubled by Meadow's evidence that he wrote a damning critique in the British Medical Journal called 'Conviction by Mathematical Error?' Meadow has not replied to the attack.

Donnelly points out that a key issue is whether Meadow was right to multiply the risk factors of the two cot deaths to get to the one in 73 million number. 'It is only valid to multiply the numbers if it has been established whether or not one child dying of cot death is completely independent of whether or not another has died. In order to present that kind of number in court one should have evidence to establish that independence.'

What this means is that, for the one in 73 million to be right, the two deaths had to be proved to be wholly unconnected - for example that there were no environmental factors common to both.

But, according to the prosecution, the two deaths were connected - and the prosecution witness who gave evidence on that? Sir Roy Meadow.

He told the jury: 'Each death has the characteristic of unnatural causes which is enhanced by the fact that two deaths have occurred at about the same age in one home. The evidence sadly increases the strength with which I feel that the two deaths are not natural.'

The defence did not use an expert statistician to challenge Meadow's figure. This decision may have cost Sally Clark dearly.

Clark is not the only alleged killer mum who was jailed with the help of Meadow's evidence. Donna Anthony is also serving a double life sentence in Durham Prison for murdering her two babies. She was convicted on forensic and behavioural evidence which, again, was contested. Meadow told the jury: 'Natural cot death has an incidence now of about one in a thousand, so the chance of natural cot death happening twice in a family is one in a thousand times one in a thousand, which is one in a million.'

We also know of a third case, but we cannot give details. Meadow's evidence and other testimony led to the family losing all four children to care. A gag on the media means we cannot interview the parents.

Last October, the Court of Appeal turned down Clark's first attempt to clear her name. Clark's father, retired police divisional commander Frank Lockyer, is convinced of his daughter's innocence: 'She'd have to be monster to do that and Sally's not a monster.'

In February Manchester University announced: 'Cot death gene identified.' Scientists looked at the DNA of 23 babies who had died from cot death or sudden infant death syndrome (SIDS) and compared it with the genetic make-up of normal babies. Babies with three particular genetic differences were three times more likely to die from SIDS. The genes 'switched on and off' the immune system. One gene was particularly important.

We have put a series of questions to Meadow, but he declined to talk to us.

The question is: had the jury known in the case of Clark that, instead of Meadow's sound-bite that there was a one in 73 million chance of her babies dying naturally, it could have been one in four, would they have convicted?

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In a recent case of DNA evidence the probability of a chance match was quoted as 20 million to one. The accurate statement - that the defendant or two other unknown people in the United Kingdom could have committed the offence - is much less impressive. Other evidence was overwhelming, but this may not always be true, especially with matches from DNA databases. Even more problematic than the issue of presenting statistical evidence fairly is the problem of getting it wrong.

On 9 November at Chester Crown Court Sally Clark, a Cheshire solicitor, was convicted, by 10-2 majority, of smothering her two infant children. With conflicting forensic evidence, the Crown's case was bolstered by an eminent paediatrician testifying that the chances of two cot deaths happening in this family was vanishingly small - 1 in 73 million. This seriously misunderstands probability theory. It is speculation whether Sally Clark would have been acquitted without this evidence. But with this mathematical error prominent the conviction is unsafe.

Imagine an archery target with two arrows sticking in the very centre of it. This provides greater evidence of the skill of the archer if the target was in place before the arrows were fired than if it was drawn around them afterwards. Probability theory requires calculation of the probability not only of the event in question but also of all events that are as extreme or more extreme. When the target is drawn first you calculate the chance of both arrows hitting the centre of the target. But when the target is drawn round the arrows afterwards you calculate the chance of both arrows hitting the same point, whatever that point. With two independent arrows one probability is the square of the other.

Suspicion was drawn to Sally Clark by the occurrence of two deaths so the probabilities should not have been squared. The odds of 1 in 73 million shrink to 1 in 8500. But this figure is itself meaningless. There is in fact a wall full of arrows with the target drawn around the two that are close together and the others ignored. Mathematical formulas for this situation often surprise people. For example, with only 23 people in a room the odds are better than 50% that two of them have the same birthday.

From whole population data Reese calculates the square of the population risk of cot death as 1 in 2.75 million. There are 378 000 second or subsequent births each year in England. So if cot deaths are random events two cot deaths will occur in the same family somewhere in England once every seven years. But cot deaths are not random events. There have been several studies of recurrence. At least one study did show no increase in recurrence rates. But several others showed recurrence rates about five times the general rate, implying recurrence somewhere in England about once every year and a half. Two studies showed even higher rates.

The fact that studies of recurrence have been done means this event is not vanishingly rare. In a case series of recurrent infant death Emery classified two cases as recurrent cot death out of 12 cases occurring in Sheffield in 20 years. Wolkind et al found five cases in their unsystematic English case series of 57 recurrent infant deaths. Both these studies distinguished cot death from accident, illness, murder, and neglect.

The prosecution used the figure of 1 in 73 million rather than 1 in 2.75 million because of the family's affluence. Yet taking data from an epidemiological group and applying it stereotypically to all members is an example of the ecological fallacy. Social class is a complex reality of interassociated circumstances - education, work, income, lifestyle, culture, contacts, residence, opportunities, social class of origin, etc - statistically summarised for use in population studies by selecting the one variable which performs best as an indicator. This does not mean that individuals have the attributes of the statistical group.

Guidelines for using probability theory in criminal cases are urgently needed. The basic principles are not difficult to understand, and judges could be trained to recognise and rule out the kind of misunderstanding that arose in this case. Never again must mathematical error be allowed to conflict with mathematical fact as if each were a legitimate expert view.

What is our profession's responsibility for the quality of expert evidence given by doctors? Medical evidence is trusted, and we must retain that situation and ensure that it is not abused. It is possible to be an extremely good doctor without being numerate, and not every eminent clinician is best placed to give epidemiological evidence. Doctors should not use techniques before they have acquainted themselves with the principles underlying them.

When errors occur we expect them to be admitted, learnt from, and corrected. Should clinical governance extend to the courtroom? Expert witnesses can hold a substantial part of defendants' lives in their hands. Defendants deserve the same protection as patients.

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A woman serving two life sentences for the murder of her baby sons has lost her appeal against the conviction. Sally Clark, a solicitor from Cheshire, has always maintained that her children, who died a year apart, were victims of cot death.

But the Court of Appeal in London rejected her claims on Monday, ruling that the case against Clark was "overwhelming" despite the support of fresh expert evidence.

After the ruling her husband, Stephen, maintained her innocence and insisted the fight to clear her name would go on.

During the hearing in July, the Court of Appeal heard that aspects of crucial evidence from pathologist Dr Alan Williams, who carried out post-mortem examinations on the boys, were in direct conflict with the views of other experts.

Clark's QC, Julian Bevan, called fresh evidence challenging Dr Williams' conclusions and supporting the proposition that the babies were victims of Sudden Infant Death Syndrome (SIDS) or at least "unascertained death".

Some of Dr Williams' findings were unconfirmed "or just plain wrong", Mr Bevan told Lord Justice Henry, Mrs Justice Bracewell and Mr Justice Richards. Statisticians were called in relation to the prosecution's assertion that the odds of two cot deaths in the same family were 73 million to one.

Clark, a 35-year-old corporate lawyer, who was given two life sentences at Chester Crown Court last November, has always denied killing 11-week-old Christopher, and Harry, aged eight weeks, at the home she shared with her husband in Wilmslow, Cheshire.

She insists that Christopher, who died in December 1996, and Harry, who died in January 1998, were victims of SIDS.

Clark, a policeman's daughter, originally from Devizes, Wiltshire, told the jury during her three-week trial that she had found both boys "limp and lifeless" and was in "complete disbelief" at having lost two children.

Her husband said outside court on Monday: "For 72 days and as many dark nights Sally and I have been waiting. Now three judges of the Court of Appeal - eminent, respected, with intellect beyond ours - decree that Sally did murder our two sons. She did not and they are wrong."

Mr Clark said the jury had been told one double cot death could be expected in a century when the true figure was five in three years.

"Wouldn't the truth have affected the jury's decision? If so, how are these convictions safe?" he added.

Expressing thanks to their "thousands" of supporters, he said he would continue to fight to clear his wife's name. "We are not the first who have had to come to this place twice, three, four times or more before achieving justice," he said. "Sally will be released and I ask you do not forget us."

Her father, Frank Lockyer, said: "As far as I'm concerned this is not a case of child abuse, it's a case of bad medicine, bad statistics and bad jurisprudence."

Declining to go into details of their next move while he was in a "vengeful mood", Mr Lockyer added: "One has to go away and reflect on these things and decide what the next course is."

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Stephen Clark, husband of a woman accused of murdering her babies, explains why she is innocent

I thought that when my first son, Christopher, died in December 1996, life could not get worse. But it did. I was there when my second son, Harry, died in January 1998, and shall never forget my desperate attempts to breathe life into him.

If that was not bad enough, early one morning Sally and I were arrested on suspicion of murder. Sally, alone, was then charged with murdering both our little boys and, after a four-week trial at Chester crown court last November, she was convicted by 10 of the 12 jurors, and condemned to life imprisonment.

She has spent Christmas, the millennium and all summer in prison. Last week, after months of frantic work on an appeal, we all gathered at the High Court in London to hear the judgment. I thought it inconceivable that we would fail, but as soon as I saw the stricken face of our solicitor the last vestiges of my faith in the English justice system died.

Sally is innocent - she did not murder my sons.

How do I know? We have been married for more than 10 years and knew each other for quite some time before that. There is a deep, abiding love and understanding between us, which means that I know her better than anyone else in this world.

It is hard to put into words how it felt to see her last week in the dock, handcuffed to a guard, both of us numb with shock and disbelief as we heard the appeal refused. I could not see her or speak to her to comfort her before or after the hearing. We expected at least the chance of a retrial.

The monster portrayed by the prosecution is unknown to us. I saw Sally with Christopher and Harry, and she could not have been more tender in her care for them. The midwives, health visitors and nanny who helped out all said that Sally was a caring, loving mother.

I saw her joy when Christopher was born, and shared in her agony when he died suddenly at just 11 weeks old that dreadful night just before Christmas. I cried with her when Harry was born - we thought that the healing process had begun - and sat with her when he died at eight weeks, numb and disbelieving in the same room, in the same accident and emergency department as 14 months earlier. Christopher was a lovely boy, blond, blue-eyed, and the apple of his mother's eye. He was no trouble at all and slept through the night right from the start. Sally was so happy organising his christening; she had booked the church, sent out all of the invitations and arranged the reception. On the morning of the day he died she ordered the christening cake. Are these really the actions of a mother intending to murder her baby?

Harry was different from his brother - more spirited. But we loved him all the more, because he helped to ease our pain. He was so precious that Sally carried him with her from room to room to make sure he was safe and well.

The prosecution painted a sinister picture of family life in the Clark household - they said that Sally was tired and depressed, and resented the interruption to her career caused by having children. Nothing could have been further from the truth.

For Sally to have murdered our two lovely little boys, she would have to be either evil or mad - and she is neither. For me to have stood by her, giving evidence on her behalf at her trial and bankrupting myself financing her defence, I would have to be as bad as she or a besotted fool - and I am neither.

All our hopes had been pinned on the thought that three appeal court judges would recognise straight away that a miscarriage of justice had taken place and would put it right, all the more so because Sally and I are both lawyers, and worked for a leading firm. Sally's father is a retired police officer.

We were all people who had complete faith in the justice system and still find it hard to believe it could have let us down.

Central to our appeal were two arguments. The first concerned the quality of the post-mortem evidence on both our boys, which we believe was badly flawed.

The second rested on a statistic I believe was devastating, and led directly to Sally being wrongly convicted. During the original trial the court heard days and days of conflicting, complicated medical evidence from nine expert witnesses.

Then Professor Sir Roy Meadows, an expert from Leeds, (a paediatrician, not a statistician) said that in a family like ours the chances of a double cot death are one in 73m. In other words, an event that would only happen once every 100 years.

This statistic is totally wrong - since the trial we have heard from dozens of families who have suffered double cot deaths, which actually happen around every 18 months - but it was one of the few things that the jury could (and did) understand.

Certainly, it was one piece of evidence that the press seized upon, and we know that the judge felt it was important from the comments he made when fixing her sentence. If it played a major role in the jury's verdict then the convictions are obviously unsafe.

The appeal court judges accepted that the statistic was wrong but said that it was of "minor significance". In addition, they disregarded our new evidence that - if one plays the statistics game - the chances of Sally having murdered Christopher and Harry was 2,200m to one.

As for the evidence against Sally being "overwhelming", Sally said to me in a tearful telephone conversation earlier last week: "How can the evidence be overwhelming when I did not do anything?"

It seems that the appeal was dismissed on the assumption that the medical findings by Dr Alan Williams, the local pathologist, were reliable. But, at trial, even the prosecution experts agreed that he had made several crucial mistakes. Every one of his findings which was capable of independent verification was found either not to exist at all or to have been misinterpreted by him as being sinister. None of the four paediatric pathologists who gave evidence at the trial has ever been able to give a definitive cause of death for either of my sons. How can that be overwhelming evidence of murder?

The guard who accompanied Sally back to jail after the appeal was in tears. All the inmates and staff were convinced she would be going home. She has been lucky in that at least she has made some very supportive friends there.

Sally's defence team now has to regroup and continue the quest for justice. We are determined that we will be back in court, somewhere, somehow, and that Sally will be returned eventually to where she belongs - her loving family, not a prison cell.

If this could happen to us, then it could happen to any parent who suffers the death of a child when the doctors do not know why - and nine mothers suffer such a loss every week in Britain.

Maybe, in the years to come, medical science will have advanced sufficiently to enable doctors to discover the real reasons why my sons died. But why should my poor wife have to pay such a terrible price for their current lack of knowledge?

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The husband of Sally Clark, the solicitor convicted of the murder of her two baby sons, vowed yesterday to continue to fight for his wife's freedom after an appeal against her two life sentences was thrown out at the high court in London.

Three high court judges rejected fresh evidence in support of Clark's claim that her children had died of sudden infant death syndrome (Sids), or "unascertained death", stating that there was overwhelming evidence of her guilt at her trial last November.

The judges also ruled that despite errors in the way statistics concerning the chances of a family losing two babies to Sids, also known as cot death, were presented at the trial, that did not prejudice the jury in considering its verdict. "If there had been no error in relation to statistics at the trial, we are satisfied that the jury would still have convicted on each count," they said.

But Steven Clark, a senior partner in a Manchester law firm, maintained his wife's innocence. "For 72 days and as many dark nights Sally and I have been waiting. Now three judges, eminent, respected, with intellect beyond ours, decree that Sally did murder her two sons. She did not. They are wrong.

"We are not the first who have had to come to this place [the high court] twice, three, four times or more before achieving justice. I take heart, for though the years may drip slowly by, sense has a way of seeping even through these walls. We will be back, Sally will be released," he said.

On hearing the verdict, his wife, 35, remained composed, dabbed at her left eye with a handkerchief and mouthed the words "I love you" to her husband. Mike Mackie, her solicitor, said: "She is in a state of shock and disbelief at what has happened to her."

The couple's children, Christopher, 11 weeks, and Harry, eight weeks, died within 13 months of each other between December 1996 and January 1998. Their mother was alone with both children at the time of their deaths at home in Wilmslow, Cheshire.

When Christopher died Dr Alan Williams, the pathologist who examined the child at Macclesfield general hospital, gave the cause of death as an infection of the respiratory tract, a form of Sids, and dismissed evidence of bruising to the child's legs and a cut to his mouth, features that were presented by the crown as evidence of abuse at Clark's murder trial.

Within three months of Christopher's death she was pregnant again - "part of the healing process," said her husband - and Harry was born. Eight weeks later he too was dead.

Dr Williams also examined Harry and detected rib damage, swelling of the spinal cord, small tears to the brain and bleeding within the eyes. It appeared to him a classic case of death by shaking.

His suspicions led him to look again at his notes relating to Christopher, who had been cremated, and he decided the bruising and cut mouth, in addition to samples taken from the boy's lungs which showed evidence of bleeding, suggested that Christopher may have been smothered. A murder inquiry was launched and Clark, who had a third baby boy following Harry's death, was arrested and charged.

At the trial at Chester crown court the jury was told that the chances of two babies from a single family dying of Sids were 73 million to one, or once every 100 years, a figure erroneously reached by squaring the ratio for one cot death in a family (around 1:8,500) and ignoring environmental and social factors.

Yesterday, the judges accepted that the figure endorsed by the judge was incorrect, but ruled that that had not rendered the conviction unsafe.

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A solicitor serving life for the murder of her two baby sons had her appeal against conviction thrown out yesterday after three judges ruled that the evidence against her was "overwhelming".

Sally Clark, 34, wept as the Court of Appeal in London was told there were no grounds for quashing the verdicts against her, despite a claim that statistics used by the prosecution at her trial misled the jury.

The high-flying lawyer was convicted last November of killing her 11-week-old son Christopher in December 1996 and her younger son, eight-week-old Harry, a year later.

Her husband, Stephen Clark, attacked the finding as "wrong" and made an emotional vow to fight for his wife's release. She mouthed the words "I love you" to him from the dock as the appeal decision was delivered to a packed court.

Standing outside the court, Mr Clark, 34, also a corporate lawyer, said: "For 72 days and as many dark nights, Sally and I have been waiting. Now, three judges, eminent, respected, with intellect beyond ours, decree that Sally did murder her sons. She did not. They are wrong."

Mrs Clark, of Wilmslow, Cheshire, has always insisted that her children died in a rare tragedy as a result of so-called cot death or Sudden Infant Death Syndrome (Sids).

Prosecutors alleged instead that the mother, who was suffering from depression during the period in which she killed her sons, either smothered or shook the children to death.

Lawyers for Mrs Clark put forward five grounds for overturning her conviction at a hearing in July this year.

Central to the appeal was a claim that evidence given by a key prosecution medical witness, Sir Roy Meadow, was incorrect. Sir Roy put the chances of two children from the same family dying of Sids at 73 million to one.

However, Mrs Clark's legal team claimed that the true figure was closer to one in 8,500, producing evidence from the Foundation for the Study of Infant Deaths that a double cot death happens in Britain once every 18 months.

In an 82-page written judgment, Lord Justice Henry, chairman of the appeal panel, said the trial judge should have dismissed the 73-million-to-one figure as a "distraction" and not directed the jury to consider the prosecution statistics.

But the Court of Appeal judge said the point was of "minimal significance", adding that the combined weight of medical and circumstantial evidence against Mrs Clark made her conviction safe.

He wrote: "We consider that there was an overwhelming case against the appellant at trial. If there had been no error in relation to statistics at the trial, we are satisfied that the jury would still have convicted on each count."

Mrs Clark, daughter of a police superintendent, had either been alone with her sons or her husband had been about to go away on business at the time of the killings, the court was told.

Also of significance was the fact that Christopher and Harry were both of the same approximate age, were found dead at almost exactly the same time (9.30pm) and had both showed signs of previous physical abuse.

The judges also criticised Mr Clark for giving "untrue evidence" at the trial about the time he returned home on the night of Harry's death. He had initially claimed he was home two and a half hours earlier.

But the solicitor, whose third son with his wife was recently returned after a period in care, emerged from the Royal Courts of Justice defiant. He said: "I take heart for, though the years may drip slowly by, sense has a way of seeping, even through these walls ... Sally will be released."