MARY ROBINSON likens the mayhem in her home to wartorn Beirut; it continues from early morning until late at night. "The children don't play together. They all want to be the centre of attention and they fight."

Any parent with young children might be tempted to describe their home like that, but this is different. Five of Mary's six children, aged between three and 13, aren't just difficult and demanding - all five are autistic.

She takes it for granted that, every week, she must change wet beds, put radiators back on the walls, repair the loo, retouch the paintwork, explain the children's black eyes to teachers and apologise to other parents if her children have bitten or kicked theirs. "What else can I do?" she shrugs.

The one thing she cannot do is relax. Thirteen-year-old Claire could be wandering off, oblivious to danger; 11-year-old Tyson might be trying to hatch raw eggs by sitting on them and Jordan, 10, could be in one of his violent moods. Hayden, nine, who cannot speak, will be screaming for her while three-year-old Leah is showing her a toy for the millionth time.

We meet while the children are at school, otherwise conversation would be impossible. Looking at the prominently displayed photographs of their angelic faces, the perfect order into which Mary has the sitting-room by mid-morning and her calm exterior, it is hard to credit the chaos she describes - or that she has a child who tells her: "When you are asleep, I'm going to stab you with a bread knife."

Nights are hellish, with the children bouncing off the walls and swinging from light-fittings. Weekends offer no respite: whereas other children go to the park or play with friends, hers can't. "It's like running a care home here," says her husband, John, "except we don't get any time off."

But they do insist on escaping to the amusement parks and animal sanctuaries near their home in Hayle, Cornwall. Such expeditions call for steely nerves as, wherever she takes the children, Mary hears people tutting about their behaviour and saying: "Why did that woman go on having children if they are all handicapped?"

Had those women time to listen to her story - or she to explain it - they would learn that none of Mary's children started off autistic; they were developing perfectly normally until something caused them to regress. Far from being someone to criticise, Mary Robinson deserves infinite sympathy. She allowed her case to be made public last week and now is at the centre of The Great MMR Scare.

"I want to protect the children from too much attention," she says, "but I could not believe it when I read that the Government is spending £3 million on a campaign to make out that MMR is 'safe'. No one I know will allow their child to have the triple vaccine, and since single vaccines are not available, there will be epidemics of measles, mumps and rubella - and children will die.

"It's all because of money. For the Government, it is cheaper to give the immunisations together, so they aren't offering people a choice. When a manufacturer is shown a single contaminated can of beans, the whole batch is recalled yet, with MMR, the Government is quoting some questionable research and not giving parents the benefit of the doubt."

As for the claims that autism has not increased, they leave her speechless. "I was once a nanny and I used to work in a nursery. I know that there are more autistic children around. When we go to special centres, I meet parents who talk about their children behaving normally and then changing - and some haven't even heard of the concerns over MMR."

Mary hadn't either when she had her children vaccinated. The triple vaccine was introduced in 1988, so her eldest, Donna, who lives with her grandparents, never had it; she is not autistic. The rest were immunised and from that moment, in each case, she charts the onset of their problems.

In fact, only three of her children are included in the legal action being brought by solicitors Alexander Harris against the five drug companies that supply the vaccine. Claire had MMR too long ago to be admissible and Jordan's case is complicated by prematurity, but Tyson, Hayden and Leah have all had their medical records checked and legal aid has been provided to bring their cases.

Other possible causes of autism can be ruled out. Mary was so anxious not to have another problem child after Jordan that she had his genes tested and later her own. No problems were found. Nor was any autism found in their families - only asthma, often involved when MMR appears to have caused problems.

Significantly, Hayden was given a brain scan as a baby - before he had the MMR jab - and found to be normal. "Until he was 18 months, Hayden was a lovely, placid child. At that age, he was saying: 'Oook, doggie'. But within nine weeks of the vaccination, he had lost his speech and wouldn't let me look at him; his whole personality changed."

Although reassured by the genetic tests, Mary was still keen to have another girl when pregnant with Leah as Claire's problems seemed so much less acute than those of the boys (although that could be because of her high intelligence). When the longed-for girl was born, Mary was overjoyed and everything went well until, two years ago, Leah had her MMR.

"By that time, there were rumours. Knowing that I had three sons registered as autistic, no one in the medical profession drew my attention to the idea that there was some concern. They said nothing. I find that unforgivable."

So Mary went ahead and allowed Leah to have the jab and history, heartbreakingly, repeated itself.

"You feel you've lost your child; it's just like a bereavement," she says.

By this stage in our conversation, Leah has reappeared from her special needs nursery. She is a charming child but her words come out strangely and she rushes around frantically.

Mary was as baffled by the early signs of these changes in her hitherto normal daughter as she had been by the onset of autism in her other children. Then she picked up a magazine containing an article about a woman with three autistic sons - and read about the concerns over MMR.

Immediately, she contacted JABS, an organisation run by affected parents, and was put in touch with the legal action group. "How likely is it that I could have had five naturally autistic children?" she asked. The chance was infinitesimal, she was told.

But Mary is not a campaigner. She doesn't have time for that, any more than she can go to church to please the Mormons who keep coming round to pray for her, or find time to train to be a social worker: "I couldn't find anyone to look after the children, so I gave up."

All her considerable practical skills are devoted to giving her damaged children as enjoyable a life as possible. "I told them all, early on, that they are autistic and that everything they feel is normal for the way they are. It's not fair, I tell them, that you have to try harder than other children, but you'll get there."

She feeds them an additive-free diet and refuses to drug them to make them more controllable. Nor will she take anti-depressants herself; when she tried, she was shocked by the feeling of swimming through treacle.

Rather than spending the children's disability allowances on running the house, she saves the money up for special toys - light pillars that produce mesmerising bubbles, computers on which they can express themselves, projectors that make patterns on the walls. Leah's room is a child's dream, crammed with play equipment, none of which can be kept downstairs, as the boys would destroy it.

And, despite the dents on the ceilings, the touched-up paint and scribble on the walls, the house has a warmth to it. So does the garden, with its aviary, rabbits and guinea pigs, trampoline and slides, all of which take the edge off the hyperactivity that comes with autism.

Although she looks young for 38, the past few years have been gruelling for Mary. Claire and Tyson's father left her when she was seven weeks pregnant with Tyson; Jordan and Hayden's father left her when she refused to put the boys in a residential home. Then she made an unsuccessful marriage: "In a situation like mine, you are so glad of help, so desperate for company"

To escape her husband and find a home large enough for the children, she and John, whom she married two years ago, have moved twice in quick succession. John, I say, must be a saint taking on all these children as well as his own daughter, Leah.

"He isn't," she replies. "He has a bad back, which means he can't work or run after them and he can't stand it for long. But he does watch them for 20 minutes while I eat my dinner in the bedroom."

Since she began eating in peace, Mary has put on a stone and given up smoking. She's pleased. "The stronger I am, the longer I can keep my children at home."

Helping them is her over-riding concern and, every year, it gets more difficult. "Jordan broods on his disabilities; Tyson has terribly low self-esteem; Hayden I now accept will never talk. I just live each day at a time," she says - never planning anything, her head constantly full of a dialogue between the "angel" voice that encourages her to be patient and understanding, and the "devil" which makes her want to scream and give up.

The future looks bleak. Claire, she hopes, will be able to get a job but Tyson, she fears, will be in constant trouble as he has no notion of property. She doubts if Jordan will be able to leave home and Hayden may have to live in an institution. As for Leah, Mary won't know for several years whether, like Tyson, she will develop Asperger's syndrome.

When things get too much, she turns on pop music and fantasises. "I would love to go on a holiday without losing one of them, to be able to communicate with Hayden, and have Leah get no worse.

"Above all, of course, I want to have my children back as they were - but I know that can't happen."

16 January 2001: Is MMR a shot in the dark?