A woman who stabbed a fellow school pupil to death in 1991 in a row over a boyfriend in a Glasgow playground, walked free yesterday from Cornton Vale women's prison.

Barbara Glover, who has been training as a beauty therapist at Clackmannan College and has also been working in the college's beauty salon in Stirling, served eight years and six months, her original sentence having been without limit of time.

The Parole Board for Scotland said a designated life tribunal convened at Cornton Vale on Monday to consider Glover's case and directed she be released on life licence.

A spokesman later told The Herald the widespread interest in the case had played a part in the decision to explain the reasoning behind the decision.

The three-strong tribunal studied updated reports from prison staff and social workers, together with psychological and psychiatric reports.

They looked in addition at detailed submissions and other material made available by and on behalf of Jim and Margaret Watson, the Dennistoun couple whose daughter, Diane, 16, was murdered by Glover in the playground of Whitehill Secondary School, Dennistoun, including their transcript of a tape recording which they had submitted.

The statement said: ''The tribunal fully appreciated the depth of their feelings in opposing Barbara Glover's release and appreciated the devastating effect the murder of their daughter, Diane, has had on their lives.

''The tribunal carefully considered the submissions and representations made on behalf of Scottish Ministers and the prisoner as well as the information submitted by Mr and Mrs Watson. Having had regard to all the information and submissions before it, the tribunal concluded it is no longer necessary for the protection of the public that Barbara Glover should continue to be confined. The tribunal accordingly directed she be released on life licence.''

Eighteen months after Diane's death, her brother, Alan, took his own life at the age of 16.

Mr Watson, 50, said yesterday the family were shattered by the decision to release Glover.

''We are just so heartbroken and stunned today that we can't speak about it. We promised our children we would seek justice but that seems impossible now. The system has let us down. Barbara Glover has shown no remorse since killing our daughter.''

Tribunal proceedings are normally confidential but the law allowed Sheriff Brian Lockhart to make a statement.

He explained the recent law changes which led to the Lord Justice General, Lord Rodger, deciding the designated part of Glover's sentence should be seven years and her entitlement to a parole hearing whose only consideration was whether she should be kept in jail for the public protection.

The impetus for this change came from European Court rulings in 1996 against the UK in the cases of two prisoners, Singh and Hussein, detained in England at Her Majesty's Pleasure. Both murdered as teenagers. The European Court held that their age had led to the form of their sentence and that their maturing had to be taken into account.

It had not been the tribunal's function to consider whether Glover had served long enough as punishment for the crime - that had been decided by the Lord Justice General. The first time the case was considered, in August 1998, parole was refused and recommendations made about Glover's future management in jail.

MSP Lyndsay McIntosh, Conservative deputy home affairs spokesperson, said: ''This is a desperate situation. I do not think this family will ever get over this. When people are sentenced without limit of time, that is exactly what it should mean.''

English campaigner Lyn Costello, whose Mothers Against Murder and Aggression group joined the Watsons in a vigil outside the prison during the parole tribunal hearing, said: ''We have been shown once again that victims do not matter in this country.''