Fifty years ago, autistic children had no legal right to schooling. But Saskia Baron's mother and father refused to give up on their son. They were among the first parents to embrace the idea that children with autism could learn – so they set up their own school

In 1961, my parents heard the word "autism" for the first time. It was used by a doctor who was examining my older brother, Timothy. He was a handsome but very troubled five year old with little speech and fixed obsessions. He had frequent screaming tantrums for no obvious reason. According to the doctor, Timothy fitted the diagnosis of autism as described by the American paediatrician Leo Kanner. My brother wasn't affectionate, he avoided eye contact and had no interest in other children. He was rigid in his routine and when he talked he mainly echoed what others said to him.

Timothy wasn't obviously mentally retarded, the term used in those days; he completed jigsaw puzzles at lightning speed and never checked the picture. He barely talked but memorised song lyrics perfectly. He couldn't read but always played his favourite vinyl records in exactly the same order by examining the words on the labels. My big brother was an intimidating mystery to me. As a family we couldn't go anywhere with him as he hated all new places and would scream, "Time to go home, time to go home, don't like it!" over and over again.

My dad recalls leaving the doctor's office with the new words "autism" and "childhood psychosis" ringing in his ears. He sat in the car with my mother, both of them silent, trying to take in what this meant for Timothy, humming in the back seat. Neither was prepared to send him away to the long-stay hospitals for the handicapped, which is what doctors in those days advised. They were convinced that Timothy could learn – he just needed the right kind of teaching.

In a room upstairs in our parents' house, there were four strange children, including my brother. They had lots of interesting toys, but the room was out of bounds for my sister and me. My parents had found a teacher for my brother, two other boys and a girl, all diagnosed with autism. At first the parents shared the costs, but soon they persuaded the then London County Council that these children could learn and it agreed to pay the teacher.

Looking back, my father thinks this may well have been the first officially recognised classroom in Britain exclusively for autistic children. A crack in the barriers to education had opened. In those days – half a century ago – children with learning difficulties and behavioural disorders had no legal right to schooling.

That little classroom in an upstairs bedroom was just a beginning. My mum and dad found other parents with similar children. Helen Allison, a dynamic American living in London, talked about her autistic son, Joe, on Woman's Hour on Radio 4, and it led to a flood of calls from parents who recognised their children in her description of Joe's unusual behaviour. Soon these parents met up. In 1962, 10 of them drafted a manifesto; their aim was to create schools, residential if necessary, and an information and advice service.

At first they called their charity the Society for Psychotic Children, but another parent, the psychiatrist Lorna Wing, suggested that the Society for Autistic Children was better; it was a new word, but less scary than psychotic. After a story appeared in the London Evening News, more parents joined and questions were asked in parliament about autistic children and their right to an education.

Official recognition brought some funding, charity appeals raised more money and in 1965 a house was found in west London. It was converted into the first school for autistic children, run by a wonderful teacher, Sybil Elgar. The Beatles came to visit and spent an afternoon there, playing with the children; John Lennon gave the society a cheque for £1,000 and autographed the only thing my mum had to hand, a box of liquorice toffees.

The Sybil Elgar school is still going today, though it has moved and expanded over the years. The Society for Autistic Children became the National Autistic Society in 1982. It has grown beyond recognition, from 10 parent members in 1962 to more than 20,000 today. It now employs more than 3,000 people in its seven schools, residential and training services for autistic adults and families. It still campaigns, but these days, it's not just parent-run, and has autistic adults on its council too with their own agenda.

Fifty years on, a handful of the pioneering parents survive; their children are now middle-aged. My father, 83, often looks back and says how no one could have predicted the future for that first generation of children. They seemed so similar when young, but are so different now. One of them has had his own business and was married for a while but struggles with obsessions and maintaining friendships – he is aware of his autism and finds it frustrating. By comparison, my brother doesn't seem to know what he is missing. These days he is very calm and easy to get along with, totally different from the aggressive and angry boy he once was.

Autistic people are often defined as high-functioning (with normal IQs and good language abilities) or low-functioning, like my brother, whose IQ is harder to assess. Autism experts and paediatricians often encourage parents to believe that lifetime outcomes are better for the high-functioning; and certainly many achieve more academically and, with the right accommodations, live a good life.

It's not automatically the case that they are happier than someone such as Timothy. He is happy when people are kind and predictable and he has the things around him that he enjoys – such as going to a day centre with art, dancing and music activities, eating roast chicken and ice cream. He's still a demon when it comes to jigsaws. My dad has never got over the sadness of not having a real conversation with him, but he doesn't think that Timothy is the tormented soul that he was as a boy.

Quite a few of the original children from the Sybil Elgar school now live at Somerset Court, near Brent Knoll, with its own farm. It was set up when they were reaching 18 in 1974. One of the founding parents, Gerald de Groot, now 80, still takes a keen interest – it's where his son Mark lives. He has campaigned to have the accommodation improved and to stop overcrowding. Before the 2008 crash, he helped to raise funding for new buildings. All the residents now have en-suite bedrooms and some live in their own flats – "I hope Mark can stay indefinitely. He is 52 now, and a creature of habit. He is happy, and he loves things to stay the same."

It's a similar story for Susie, the one girl in that little classroom in my parents' house. She also lives at Somerset Court. She still doesn't speak, but is an excellent weaver, sings beautifully and is happy and calm in comparison with the hyperactive child that she once was. Her mum told me, "You just have to accept them for who they are. If you want children, you can't say, 'Oh, I didn't mean someone like this!' You have to get on and do the best by them. We were so lucky that your dad and the other parents worked so hard to set up the school and Somerset Court. I'm so glad that I don't have to worry about Susie."

Some of that first generation live in small group homes and some live independently. About 18% of people with autism over 45 still live with their families. Another Sybil Elgar school graduate, the artist David Braunsberg, lives with his mother. He loves his work, supporting refugees at a drop-in centre. David is high-functioning and talks fluently about what it's like to have autism. He can get depressed and anxious as he is extremely sensitive to the attitudes of people around him and vulnerable to bullying. But in the right company, David thrives and makes beautiful etchings and silk paintings, which he exhibits and sells through his website.

Mandy, another girl with autism from David's class, grew up to marry a Dane with high-functioning autism. They had a son together, who was not on the autism spectrum and managed their family with neighbourly support. Sadly, a few others have died too young, from the effects of severe epilepsy (which often goes along with autism) or from other health problems that are sometimes triggered by the condition.

At a grand party held to celebrate the 50th anniversary of the National Autistic Society, in a room crowded with people with autism and their families, I asked my father and Gerald de Groot if they had ever imagined such an occasion when they started the charity. My dad said that they thought it would only be necessary for a few years. In the 1960s he'd believed that, as autism became more recognised, the state would provide the right schools and information for parents. De Groot is surprised that scientists still don't know what causes autism, although professionals are much better at recognising it today. When his son Mark was diagnosed in the 1960s, autism was thought to be very rare, affecting only four children per 10,000; today the rate is around one in 100.

Arguments rage about whether there is an actual increase or whether we now call people autistic who, in the past, would have been given other labels: eccentric, loner, mentally handicapped, antisocial, educationally subnormal and worse … Certainly, when Lorna Wing formulated the idea that autism was a spectrum, with degrees of impact, it led to an increase in the numbers of children and adults being diagnosed.

While scientists and the media debate whether something "out there" is causing autism rates to rise, or whether it's just awareness, not incidence, that is increasing, one issue that always worries parents is ignored. What happens when they are no longer around to look out for their children? What happens to people with autism as they age? One of my brother's peers was recently diagnosed with dementia in his early 50s. The staff at Somerset Court are working out how to keep him safe and happy.

No one knows whether dementia affects autistic people more than the general population – it's well documented that people with Down's syndrome are at higher risk of early onset dementia. But there is hardly any research on how the autistic brain changes in adulthood, or planning for how and where autistic older people should live.

The energy that drove my dad to start the first school still drives him; he looks at my brother and wonders what's happening inside his head and what his future holds. He worries about Timothy and his peers' old age in an era of cuts to social and medical care, knowing that even in the good times, the elderly and people with learning disabilities are so very vulnerable.

• National Autistic Society, autism.org.uk