A woman jailed for life 10 years ago for a double murder was freed today by the Court of Appeal. Three judges in London ruled that the convictions of alcoholic vagrant Mary Druhan, now in her 50s, were "unsafe".

Several people in the courtroom wept as Lord Bingham, the Lord Chief Justice, sitting with Mr Justice Alliott and Mrs Justice Steel announced the decision.

Druhan had appealed against her conviction at Reading Crown Court in June 1989 for murdering Richard Duddie and Kenneth Challenger, who died in a fire at a squat in Kingston-upon-Thames, Surrey.

She consistently denied being present at the house. Druhan's first appeal failed in 1990.

Her case featured in a Trial and Error television investigation six years ago and was referred back to the Court of Appeal by the Criminal Cases Review Commission, which inquires into possible miscarriages of justice. As she emerged from the cells to be greeted by tearful members of her family, Druhan said: "I'm free. I'm free. I'm free."

Asked how she felt, she said:"I don't feel anything. I feel numb. I would like a nice cup of tea and a Cornetto. It was hot in there. The worst thing was when I first went to Holloway. It was very frightening."

She thanked her family for their support, and her counsel Helena Kennedy QC. Questioned about her plans for the future she said: "I have not given it much thought."

Her solicitor, Kate Akester, said outside court: "We will be putting in an application for compensation as quickly as possible, given that the appeal was allowed on information not disclosed about one of the main prosecution witnesses." Lord Bingham said that on the evidence as it now stood, the trial jury would have been bound to conclude that however strong the grounds for suspicion, "proof was lacking".

Druhan, who had been sentenced to two terms of life imprisonment to run concurrently, sat in the dock today dressed in a smart blouse and jacket to hear the court's decision.

During the earlier appeal hearing the court heard that she was convicted partly on the "inconsistent" evidence of fellow vagrants living in an alcoholic "nether world". There was no scientific evidence against her.

Lady Kennedy said that two witnesses who pointed the finger at Druhan as the person responsible for starting the fire, were, like her, part of a vagrant community whose members were known for their volatile and unpredictable behaviour.

She referred to the "slippery" quality of the evidence given by people with fragile and dysfunctional personalities. Their consciousness of time is wholly unreliable. Days melt into days and a sense of real time doesn't exist for them," she said.

Lady Kennedy said that Druhan's accusers, Robert Smith and a man called Neary, had given markedly different accounts of what happened. Neary was now dead. Smith, whose whereabouts were unknown, had subsequently been linked to two other fires at derelict houses, in one of which a woman died.

Lady Kennedy called fresh evidence during the appeal about the past character of a third witness whose testimony was relied on by the Crown at trial.

Lord Bingham said today that the evidence of this third prosecution witness, although given in good faith and without malice, was "seriously exaggerated". His evidence concerned Druhan's behaviour during a drunken scene at a pub before the fire. Lord Bingham said his accounts of what transpired "were by no means consistent".

There was also a failure to disclose the details of this particular man's criminal record for forgery and shoplifting, and his background involving drug addiction, which Lord Bingham said had deprived the defence of an "important opportunity to undermine his credibility as a witness".

Lord Bingham said that by an "unfortunate oversight" this witness's criminal record was not disclosed in the lists of convictions supplied to counsel for the Crown at trial "and not disclosed at all to the defence". Had that been done the man's drug addiction and treatment would have come to light.

Members of Druhan's family said after the ruling that they were "delighted and in a state of shock". Druhan had come to England from Ireland to work as a nurse in a private hospital when she was a young woman. However, after her husband died, she had turned to drink and mixed mainly with fellow drinkers, living rough or in squats. Evidence over the sequence of events on the night of the fire were disputed, but she was convicted on June 12, 1989.

Trial and Error featured her story, pointing to what it suggested were many discrepancies in the case against her and staging a reconstruction of the alleged murder.

Lord Bingham said today that the prosecution case as it emerged at her trial had certain strengths, but had faced what the Court of Appeal had found were 17 "inherent problems".

Razia Karim, legal officer of Justice, the legal reform pressure group which has been working on Druhan's case for seven years, said later: "Justice is delighted by the court's judgment; it is a great day for Mary and her family. However, Mary Druhan's case, like so many cases before it, underlines how non-disclosure of evidence is one of the key causes of miscarriages of justice. Given that the new regime in the Criminal Investigations Procedure Act 1996 makes disclosure even less likely, the number of miscarriages of justice cases is set to increase."

David Jessel, presenter of Trial and Error,which featured Druhan in its first programme in 1993, said the evidence against her was so unreliable she should "not even have been brought to trial".

A 28-year nightmare which began when "a perfectly normal wife and mother" found her husband dead in bed beside her came within hope of an end yesterday.

Mary Druhan, now in her 50s, walked free from the appeal court after spending 10 years in prison for a double murder. Three judges agreed the conviction was unsafe.

The deaths occurred in what was described in court as "the nether world" of alcoholic vagrancy into which the death of her husband plunged her.

Her first words, as she was greeted by weeping members of her family after her discharge, were: "I'm free, I'm free, I'm free."

Then she said: "I would like a nice cup of tea and a Cornetto. It was hot in there."

Asked how she felt, she said: "I don't feel anything. I feel numb."

Mrs Druhan's case was first raised seven years ago by the Channel 4 programme Trial and Error, for which the result is a triumph.

As a young woman she came to England from Ireland to work as a private nurse. She married her husband John in the 1950s and had two daughters. John died in April 1971.

Trial and Error's producer, Steve Haywood, said outside the court that Mrs Druhan's fate showed "how tenuous can be the hold we all have on what we believe to be reality.

"Until John's death, she was virtually teetotal. After he died, she continued to lay a place for him at table.

"She began drinking without anyone knowing. This intensified. She lost her home and her job." She lived in squats and derelict houses, searching the riverbanks in her home town, Kingston upon Thames, Surrey, every morning for dregs of beer in discarded cans.

In 1989 she was convicted of murdering two alcoholics, Richard Duddie and Kenneth Challenger, by causing a fire in a squat at Kingston. She denied being in the house.

She lost her appeal against conviction in 1990. But last year the criminal cases review commission referred her case back to the court.

In the hearing which led to her discharge yesterday, her counsel, Lady Kennedy, said one of the trial witnesses against her had subsequently been linked to two other fires in derelict houses. The other [witness] was dead.

Both had given markedly different accounts. Lady Kennedy spoke of the "slippery" quality of evidence given by people with fragile and dysfunctional personalities.

"Their consciousness of time is wholly unreliable. Days melt into days and a sense of real time doesn't exist for them."

Yesterday Lord Bingham said a third witness's evidence of a drunken pub scene before the Kingston fire was inconsistent. His criminal record for forgery and shoplifting had not been disclosed at the trial. This deprived Mrs Druhan's defence of an important chance to undermine his credibility.

Outside court her solicitor, Kate Akester, said: "We will be putting in an application for compensation as quickly as possible." Family members said that they were "delighted and in a state of shock"

Mr Haywood said: "She has not drunk in prison, although alcohol is known to be available there. "Now she is going out into the world with a support structure around her."

Asked about her future, Mrs Druhan said: "I have not given it much thought."