“Simon was born with ADHD. Right from the beginning he was different from other children. He was restless and fractious and couldn’t feed or sleep properly, to the extent that the local hospital offered us respite care.

“By the age of two, we were having great problems. You couldn’t put him in a pram or a buggy, and he made strange whining noises all the time. Bathing and dressing him was very difficult. He was very inflexible.

“Then the whining gave way to talking. He was never, ever quiet. He never stopped moving and he never stopped talking. When he reached five and was expected to sit at a table at school, there was no way he could do it. He simply could not inhibit either himself, his speech, or his reaction to things.

“The only help on offer was child guidance. Which leans towards the idea that if you manage your child properly, the problem goes away. We went up a lot of blind alleys. By then, my marriage had broken up. There was no normal family life left. We couldn’t have one. And you become ostracised socially because your child is seen to be beyond your control.

“The turning point was when Simon was eight. I went to school for a sports day and his teacher shouted at me down the corridor ‘Mrs Brewer. I could strangle your son!’ He was spending most of his time at school standing in the corner facing the wall, still talking.

“I took him out of the local primary school, and found a weekly boarding school willing to take him on. In the same year, 1990, I found Professor Peter Hill at St George’s Hospital. I went along with all the case notes, and my diary of the things that were happening to us. I’d always felt that there was something wrong, that it wasn’t Simon’s fault.

“Professor Hill and I sat down for a long, long time. At the end, he said ‘you’ve been telling this story for many years. But nobody’s heard it till now.’

“Professor Hill described him as one of the most severely-affected children he’d seen, and said did I want to think about medication. It didn’t take much thinking about. I couldn’t really control him any longer, and I was beginning to fear the time when I would have to think of him going into care.

“I accepted medication for him with my eyes wide open, knowing that all medicines have side-effects, and that we were looking at the long term. It was that or giving up.

“I started with a very small dose, expecting miracles, and nothing happened at all. I gradually increased the dose until it reached 15 milligrammes in the morning, and 15 in the afternoon, and for the first time in his life he stopped talking. He was nine.

“One night around that time, he sat in the bath and he took my face in his hands and really studied it. He said ‘Mummy! I can see your eyes.’ I said ‘yes, darling, and I can see yours’. We’d never had eye contact. We began to build a relationship - to hug and kiss and look at books and talk with a proper dialogue, taking turns to speak. It was slow.

“He seemed emotionally so much younger than other children, because of all the things he’d missed out on. And most importantly his self-esteem was almost on the floor. Ritalin, if it works, gives room for a few small successes. Even if it is just getting dressed without being yelled at.

“Even on Ritalin, Simon still needs a lot of support, and constant reminding of what he’s supposed to be doing. We had him statemented, but we’ve had no help from the London borough of Merton. Because his academic performance was judged age appropriate, they said he could go into the local comprehensive of 1,000 children, and get perhaps a few hours support a week.

“He’s in a small private school which groups children by their emotional age, and whose whole ideology is geared to the emotional growth of children. It costs nearly Pounds 4,000 per term, and I get no help from the LEA.

“We find ADHD children who are in schools that are punishing them, standing them up in assembly and calling them stupid, it’s enough to switch them into a very, very aggressive mode. The only reason I can save Simon from all this is because I can pay for it.”