Staleness sits around the house. The brown furniture, old-fashioned piano and fading photographs suggest time died in December 1995 when its owner, Philip Lawrence, was stabbed to death. Philip, headmaster of St George’s Roman Catholic school in west London, died trying to stop a 12-strong gang bludgeoning one of his pupils with an iron bar. Ever since, his widow Frances has tried to make sense of her loss, fighting a lone crusade for reform of the criminal justice system.

Last week her fragile equanimity was shattered by an e-mail from the probation service, alerting her to the next day’s edition of The Sun which was to reveal that her husband’s killer, Learco Chindamo, now 25, was being allowed out on day release as part of a “resettlement programme”.

He had apparently spent the previous Saturday in London being treated to a meal out by family and friends. On the way back to Ford open prison in West Sussex, the car in which he was a passenger was stopped by police on the M25. They were astonished to find Chindamo inside.

“If it weren’t for The Sun I would not have been told,” suggests the quietly spoken teacher. “I am in touch with families of other murder victims and one woman in Wales tells me the first she knew of the release of her husband’s murderer was when she bumped into him in the village shop. And,” Lawrence adds, “I am sure that is not an isolated case.”

By hideous irony, Lawrence reports that her son Lucien happens to be studying not far from Ford open prison. And ever since the murder Lawrence, having become a pseudo-celebrity, has had to endure a stalker. “This is one of the awful consequences you only learn later: as well as being forced into a relationship with the perpetrator (Lawrence attended each day of the five-week trial), you are caught up in this criminal world.”

A rare dash of colour on the mantelpiece of the west London house that she shared with Philip is a sunny snap taken in their garden; Philip clutches a glass of lemonade surrounded by his carefree wife and chirpy brood of four. Lawrence runs herself down but has surely done a remarkable job: she reveals two of her now grown-up children are teachers, a perfect tribute to their father.

“I wanted them to forge their own lives,” says Lawrence, stroking her neck beads, “but to put something back into the society that had wronged them.”

Despite such magnanimity, life remains hard: “My youngest daughter has battled against the odds and is to sit her medical finals. How do you think she feels (about her father’s killer being released)?” Pause. “She is called Unity: we loved the idea of a united family. Some irony.”

Lawrence emphasises that her concerns are practical as well as emotional. The killer of John Monckton, the Chelsea banker, committed the crime while on early release. Lawrence was once telephoned by an “angry” probation officer who told her that she should apologise to her husband’s killer, for this would make the young man “feel much better”. Lawrence’s crime? Failing to recognise that Chindamo had, supposedly, repented in advance of an (unsuccessful) appeal.

“It was one of the worst moments of my life,” she says. “I was about to take a class and was told there was an urgent call. I looked back over what I had said and I had not even claimed Chindamo had failed to repent. He had apparently written a letter expressing some regret, but when I investigated I discovered this was written as an academic exercise, not a voluntary expression from the heart. Ever since Philip’s death I have felt I am living in an Alice in Wonderland world.”

Curiously Lawrence gets a mixed press. She is carted out by tabloids seeking a “no mercy for murderers” voice, but is actually meek, moderate and — in brief bursts when the foggy grief rises — merry. She distances herself from “hangers and floggers” and, remarkably, says that she wants her husband’s killer to lead a “fulfilled” life.

“The instant he killed Philip he destroyed his own life,” says Lawrence evenly, but then emotion gets the better of her. “It would mean far more to me if he made something of his life. It was guys like Chindamo who Philip was trying to help.” Pause. “He (Chindamo) deserves as much help as my own son.”