Frank Johnson spent more than a third of his life in prison for a murder he did not commit. He was 40 when he was convicted of dousing his mentor and employer in petrol and setting him ablaze. He was 66 before his protestations of innocence were finally heard.

During the 26 years he fought for justice, Johnson lost his partner, his children and all contact with his past life. When his conviction was abruptly quashed midway through an appeal hearing last Wednesday, he was left on the pavement outside Swaleside prison on the Isle of Sheppey with nothing but three large sacks of evidence and a small bag of clothes.

'I don't have anything, not even an identity,' he told The Observer. 'I don't have a birth certificate, National Insurance number or passport: I have no way of proving who I am. After 26 years of being a prison number, I am now not even that.'

But instead of railing at the injustices, Johnson has managed to forgive those who conspired, both deliberately and through complacency, to tear his life apart. 'I don't hold any bitterness, I just feel sadness,' he said from the east London house of Billy Power, one of the Birmingham Six, who, along with MOJO, the Miscarriage of Justice Organisation, has fought tirelessly for Johnson's release.

'Sometimes understanding is more important than knowledge. I understand why Mary, my partner, left me; the kids were very young,' he said, leaning forward in his chair with an almost Zen-like calmness and confidence.

'There is nothing I can do about the past. That time has gone; it's finished. I know it's a sin, but you have a very short life on this planet. Sometimes you just have to go along with it and I have to look ahead now.

'I have plenty of time to think in here - I mean I had plenty of time when I was in prison,' he corrected himself. 'The war in Afghanistan, the twin towers, the floods in Bangladesh that flush away entire villages year after year. Society is fundamentally unfair and I was just dealt a bum hand.'

Johnson was convicted of murdering Jack Sheridan, a shop owner who provided a home and became a father-figure to him and his young family in the early Seventies, by setting him ablaze in the store where they both worked in Whitechapel, east London.

Although it was Johnson who put out the flames and called the police, he was arrested 10 months later after two co-defendants, Jack Tierney and David Smart, fingered him as ringleader.

Johnson could have been freed years ago, alongside Tierney and Smart, if he had admitted guilt to a parole board but, determined not to leave prison with a conviction against his name, he refused to give up.

His struggle ended when Lord Justice Longmore ruled it was 'impossible' for his conviction to be classed as safe after evidence that he was suffering from a mental disorder at the time of his trial.

'I am furious that I was let off after all this time on a technicality,' Johnson said. 'But I got angry with the system for a long time and it didn't hear me. Now I have learnt not to worry about things I have no control over. If you are fighting to swim against the tide on your own, you are going to lose.'

Johnson, who twice sacked his legal team before his trial began in September 1976, represented himself in court. Although he lost the case, he maintains it is not only why he is free but is also the only reason he is still sane.

'It was only decades later I found out that Tierney was a police informer and agent provocateur, and that Smart was a former soldier,' he said. 'In the anti-Irish climate of the time, I was going to be found guilty in that court no matter what.'

Johnson lost the case but he kept his papers. 'And I knew, somewhere in their depths, was proof of my innocence,' he said. For Johnson, that knowledge was enough to cling to.

'The Birmingham Six had each other for support, but I only had me. When you are alone in the prison system, you are absolutely slaughtered, but because I had proof of my innocence with me every day I was never hopeless. It was just a matter of getting the right person to read it. '

Johnson needed to wait until the Birmingham Six won their freedom 15 years later before he could find that person. In 1991, Power asked Gareth Pierce, his solicitor, to take on Johnson's case.

'One of the reasons I am so calm now is because I had a goal that, no matter how far away it was, I always knew was there,' he said.

Paddy Hill, another member of the Birmingham Six, the founder of Mojo and a close friend, maintained that Johnson, who has not been offered counselling, support or other form of help to reintegrate into society, is still in a state of deep shock and denial at the world into which he has been released.

'The problems suffered by people like Frank Johnson are not realised by the people themselves until at least a year after their release,' he said. 'It is once the limelight disappears and they have to get back into modern society that they realise their loss and what they have suffered. Their problems have been compared with Vietnam veterans and those who have lost limbs through motor accidents.'

His concern is shared by Power. 'I would be amazed if he was genuinely as well-adjusted as he appears to be at the moment,' he said. 'I don't want to say it, but I do think the anger, upset and disorientation will come.'

A man who spent 26 years in prison protesting his innocence of murder was freed yesterday after three judges ruled that his conviction was unsafe.

Frank Johnson, 66, always insisted that he did not kill Jack Sheridan, a 60-year-old shopkeeper, by setting him alight in East London in 1975.

Mr Johnson, who was convicted of murder in September 1976 together with two others, had turned down the chance of parole and leaving jail years ago, saying that he wanted his name cleared of the crime. The other men, Jack Tierney and David Smart, have been freed on parole.

Mr Johnson's friend and employer, Jack Sheridan, was doused with petrol and set alight on February 3, 1975. He had been watching television in the back of his newspaper shop in Whitechapel. A man entered the shop and as Mr Sheridan returned to the counter, petrol was thrown at him and a match struck. He died three weeks later in hospital.

On the second day of Mr Johnson's appeal at the High Court in London, Lord Justice Longmore, sitting with Mr Justice Wright and Mr Justice Rougier, said that they were quashing the conviction.

They had been told that Mr Johnson was not mentally fit to appear at the murder trial in 1976. Lord Justice Longmore said: "We have come to the conclusion that in the light of the medical history of this case, the medical evidence, it is impossible for us to say that Mr Johnson's conviction is a safe conviction. It will therefore be quashed."

The court had been told that Mr Johnson had been suffering from paranoid psychosis. "The appellant was unable to participate effectively in his trial by reason of his mental state," Edward Fitzgerald, QC, Mr Johnson's barrister, said. The judges ruled that there was no need for any further submissions in the case, and added that they would give reasons for their decision today.

Mr Johnson, who will now be able to apply for compensation, had waived his right to appear at the court and was discharged last night from Swaleside prison on the Isle of Sheppey in Kent.

He emerged from the prison gates and embraced Billy Power, one of the freed Birmingham Six, with whom he will stay until alternative accommodation can be found.

He said: "I am so glad to be free. I thought this day may never come. I am over the moon. The first thing I am going to do is go for a pint in an English pub."

The case was referred to the Court of Appeal by the Criminal Cases Review Commission, which investigates possible miscarriages of justice. During yesterday’s short hearing Victor Temple, QC, for the Crown, held that the conviction was safe.

He said: "I do not argue for one moment other than there was some disability accrued to him, but the extent of that disability was not such as to make this trial unfair."

Mr Justice Rougier asked him: "How can it be a safe conviction if this man should never have been tried at all?" While Mr Johnson’s solicitor, Gareth Peirce, welcomed the judges' decision, she said that she was concerned that the Prison Service had not prepared her client for the outside world. She said that he was "a bit of a loner", with no family and he had not been in an open prison to accustom him to leaving prison.

"Effectively you're in prison one moment and outside the prison gates the next," she said. "It's an extraordinary situation and one that the Government needs to address."

Ms Peirce continued: "He's always assumed his conviction would be quashed. The only problem is that it's taken 26 years. It is bringing to an end a prolonged period of imprisonment when Mr Johnson could have been out years ago had he acknowledged guilt and had he co-operated with the life review board. He has consistently said he would do no such thing."

She added: "If his conviction had not been quashed today, one could imagine, the system being what it is at present, he might have remained in prison for the rest of his life."

A man who has been imprisoned for the past 26 years could be freed this week when the court of appeal considers important new evidence that, if disclosed, might have prevented him from facing trial.

Frank Johnson, 66, has been protesting his innocence since he was jailed for murdering newsagent Jack Sheridan by setting him ablaze in east London on February 3 1975.

If Johnson had admitted his guilt to a parole board he could have left prison years ago, but he insisted that clearing his name was more important than leaving jail with a wrongful conviction still staining his character.

A three day hearing starting tomorrow will consider a report by the criminal cases review commission, which referred the case back to the court of appeal three years ago.

The document includes a statement taken from Mr Sheridan shortly before he died in which he dismissed suggestions that Johnson was involved in the attack.

He described Johnson as "a grand lad", and gave evidence that undermined the prosecution's motive. Police had denied that the statement existed and said that Mr Sheridan had been too unwell to answer questions.

Mr Sheridan, 60, died three weeks after he was attacked in his shop in Whitechapel.

Johnson, who was a friend and employee, was watching television in the back of the shop at the time. He said he raced to help Mr Sheridan, threw water over him to douse the flames, then called the police and an ambulance.

He was arrested 10 months later on the evidence of two co-defendants, Jack Tierney and David Smart. They claimed that Johnson had encouraged them and was the leader of their gang.

Johnson admitted to police that Tierney, whom he knew from prison, had once suggested to him robbing Mr Sheridan's shop. But he insisted that he had turned him down flat.

Tierney and Smart also suggested that the motive for the robbery was £4,000 that was hidden in the shop. The statements of the two men were the only evidence against Johnson and all three were convicted of murder in September 1976.

While Tierney and Smart have long since been released, Johnson turned down the chance of parole by insisting he was innocent.

When the lawyer Gareth Peirce took up his case in the early 1990s, she uncovered a statement from Mr Sheridan that had been taken while he was in hospital. Asked by an officer if he thought Johnson had had anything to do with the attack, he replied: "No Frank wouldn't do a thing like that." He also said that there was only £100 in the shop at the time - not the £4,000 claimed by the prosecution. In interviews from jail, Johnson has said he had no reason to harm Mr Sheridan.

"He gave me a job and somewhere to live and he was my friend. If I needed money, all I had to do was ask for it. Even if I wished to rob the old man, which I did not, I had plenty of opportunity to do so without involving Tierney and Smart."

Mojo, the miscarriage of justice campaign group, warned yesterday that the case was not the only disturbing one in the system. "Ten years on from high profile cases such as the Guildford Four and the Birmingham Six, we're still seeing terrible cases like this, where someone has been in jail for more than 20 years."

The murder conviction of a man who has been protesting his innocence from jail for 23 years was yesterday referred to the court of appeal following the disclosure of evidence that might have prevented him being charged.

The decision by the criminal cases review commission (CCRC) has given Frank Johnson hope that he will finally be cleared of killing John Sheridan by setting him ablaze in east London in February, 1975.

The appeal court will consider a statement from Mr Sheridan taken before he died which appears to substantiate Johnson's claim that he was not involved. Police denied the document existed, but it emerged two years ago.

Mr Sheridan, a newsagent, was in the back of his shop in Whitechapel when a man appeared at the counter.

As he went to serve him, he was doused with petrol and set alight. Johnson, a friend and employee, was in the shop and was initially praised by police for putting out the flames. Mr Sheridan died three weeks later.

Police wondered whether the attack was linked to the IRA: republican fund-raising leaflets were found in the shop and it was thought Mr Sheridan had paid the price for ignoring them. Police then decided robbery was the motive.

Johnson was arrested in December 1975 on the evidence of two co-defendants, Jack Tierney, a police informer, and David Smart, a former soldier.

The prosecution said three conspired to rob Mr Sheridan of £4,000, which were hidden in the shop.

Johnson, who has previous convictions for robbery, theft and violence, was the ringleader, the Old Bailey jury was told. All three were convicted of murder in September 1976. Tierney and Smart have since been released.

Both men were linked to covert anti-terrorist operations and Johnson's supporters suspect the attack was planned to smear the IRA.

The pressure group Liberty has called for the case to be re-opened and Johnson, who came to London from Ireland in the 1950s, has forsaken the chance of parole by insisting he is innocent.

Johnson was refused leave to appeal against the conviction by a single judge in March 1977, and by the full court of appeal in November 1977.

In an interview from jail he said: "If I needed money, all I had to do was ask Mr Sheridan for it. Even if I wished to rob the old man, which I did not, I had plenty of opportunity to do so without involving Tierney and Smart."