Martin Percy's grave in a quiet Berkshire churchyard lies under a tree, unmarked save by a small basket of plastic flowers. When his mother Jeanne visits, she finds she is unable to do anything but sob her heart out. She intends to erect a proper carved headstone but cannot decide between a conventional 'At peace at last' epitaph or the angry shout: 'He was a victim of the system.'

Mrs Percy's eldest son, Martin, was born mentally handicapped, and died aged only 32 when he wandered unsupervised out of a privately run residential home, lay down in the road and was killed in a four-car pile-up.

It was a tragic conclusion to a life that Mrs Percy describes as a travesty, one long battle from beginning to end. 'What I realise now is that we were at war with the health authorities about Martin for 32 years,' she says. 'There has never been a caring, supportive system. Almost everything we tried to do for Martin was met with obstruction and rejection.'

Instead of closing the book on this sad chapter of her life, Mrs Percy, 61, is battling on to win retrospective justice for Martin and to focus attention on what she sees as an acute and continuing crisis in the care of the mentally handicapped.

In the mid-Eighties Jeanne and her husband, Derek, tried to have Martin admitted to Clarefield Court hospital, close to their home in Maidenhead, Berkshire, but were unsuccessful because it was already threatened with closure. Now, in Mental Handicap Week, she is at the forefront of a last-ditch campaign to find a charity to step in and save the hospital.

Last week, the local health trust won a planning appeal allowing it to build houses on the site. Two purpose-built bungalows for the mentally-handicapped would be included, but Mrs Percy believes that it would not provide adequate care for those as profoundly handicapped as Martin was.

She is also set to launch legal proceedings against Dorset social services department and against the Krystle Health Care group which managed Binnegar Hall, near Wareham, where Martin met his death. At the inquest last year, the coroner recorded a verdict of accidental death aggravated by a lack of care, but Mrs Percy reckons corporate manslaughter would have been more appropriate.

'Social services must take responsibility,' she says. 'Hooligans can be done for manslaughter and I see no reason why people sitting in grey suits behind desks who have taken bad decisions should not be equally accountable. Just because they look respectable, they get away with it. They make mistakes, use poor judgement, and as a result, people like Martin get killed. Nobody is accountable.'

She is angry that she and Derek were never told that Martin had left the home and crossed the busy A352 road alone five times before. She blames Dorset social services staff who advised against electronic gates at Binnegar Hall, even after several residents had left the grounds. And she is bitter that Bromley social services, which paid pounds 2,362 a month for Martin, who was born in Kent, has failed to take any legal action.

She feels Martin was let down throughout his life, from the sad day in 1961 when she walked into Farnborough Hospital pushing her gorgeous baby boy in his pram and walked home without him.

She still weeps at the memory of the smiling infant who started having fits and stopped smiling. Doctors tried drug therapies known at the time, but advised Mrs Percy to place Martin in a mental hospital and start her family again.

He stayed in Farnborough Hospital's paediatric wing until he was four, and was then transferred to Darenth Park, also in Kent, one of the massive Victorian institutions at which everybody now shudders. 'I was so nave. After three months I asked to see his doctor to find out whether he was making any progress. I thought you went to mental hospitals to get better.'

What she discovered was the hospital's policy of managing and containing patients, rather than treating them. She pressed repeatedly for transfers to another, smaller unit, tried to get Martin into a Rudolf Steiner home, asked about a new day-centre for the mentally handicapped. She dabbled with homoeopathy and acupuncture, regarded with suspicion in the Sixties. And she tried having Martin at home.

It didn't work. Mrs Percy enjoyed having her family together - she has three other children, Duncan, Lisa and Sophie - but Martin was hyperactive; he climbed like a monkey, swung from light fittings and outran his parents. On one outing he dashed into the middle of a boating pond and refused to come out.

Mrs Percy was convinced that Martin was autistic, although the National Autistic Society, formed in 1962, said he did not fit the accepted pattern.

Shortly after the Percys moved to Maidenhead in 1972, she contacted the Harley Street paediatrician who had seen Martin as a baby, and asked for an updated diagnosis. 'It was a moment of rare brightness. Within hours, this eminent man rang me personally, 10 years after seeing Martin, and asked how he could help. We got our diagnosis. Martin was a classic autistic.'

But Martin was still not given a place in a special school near Maidenhead. Instead, he spent some of his most troubled years at Church Hill House Hospital near Bracknell, kept in the repressive atmosphere of the Orchard Way ward.

Mrs Percy says Martin was a classic absconder. He would go through doors because they were there, but with total aimlessness. He was a handful, but quite without malice.

Some nurses were kind. One taught him to use a lavatory at the age of 25. He had not been incontinent - simply in the habit of choosing his own corner, like a small animal. Others subjected Martin and his fellow patients to a reign of terror. In 1982 four nurses were tried at Reading Crown Court on 32 counts of ill- treating and abusing patients. Two were jailed for three months and two for two months. They were released after a matter of days, pending an appeal, at which their sentences were suspended.

Mrs Percy is bitter at that: 'Martin was whipped on his bare back on Christmas Day. He was held under a chair by his ears like a dog with the nurse's legs wrapped round his neck. These poor patients were trapped, without speech, without any way of saying what was going on, for over a year. Yet the appeal court judges said that because the nurses had had the worry of going back to prison they should be let off.'

Despite the prosecutions, the Percys still felt unhappy about some aspects of care at Church Hill House. They initiated a shared care regime, with Martin coming home for part of each week, which lasted for about a year. The strain was considerable, so a few years later Mrs Percy leapt at financial rule changes which made it possible to claim from the London Borough of Bromley, the county of Martin's birth.

In September 1991, Bromley financed their sending Martin to a new home, Binnegar Hall. At first all went well, but then the Percys began to develop niggling doubts about the quality of supervision. They were relieved when they were offered their long-sought dream of a place at a specialist autistic home. That was four days before Martin was killed.

'The last time we saw him, he walked away to take up his customary position, lying on the floor, just looking with his lovely, lively, sparkling eyes,' says Mrs Percy. 'Martin was so gentle, he never hurt a thing, he never uttered a harsh word. He was aimless and amiable, lost in a world of his own most of the time, but there was humour and charm.'

Her experience with her son is still what spurs Mrs Percy to campaign against the closure of local mental hospitals and for the proper provision of care and back-up for the mentally handicapped and their families. Putting profoundly handicapped adults in isolated homes 'within the community' will not benefit them, she believes. They need a sheltered community, providing not just accommodation but leisure facilities, respite care and day care.

Despite suffering a heart attack in February, Mrs Percy sets to work every morning in her living room, surrounded by files, letters and research papers, ready to bombard people with phone calls and letters.

'It isn't just Martin. It's a story that is being repeated countless times all over Britain. Health trusts simply operate a huge employment industry on the backs of the mentally handicapped, all training schemes and advancement. They don't do what's best for the individual. They don't even interpret the Government's guidelines properly.

'The whole policy of care in the community is dependent on families and that means on mothers. Why should they be penalised? I have seen marriages break up, I have even seen one mother just die of heartbreak.'

(Photographs omitted)