“You’re not going out dressed like that” (she was wearing a belt that passed as a skirt, and a string vest). Second, to my son: “You treat this house like a hotel” (I think he’d actually rung down for room service). I expect they’ll get over it and say the same things to their children in time. The third thing, which I’ve waited 25 years to say, was: “George, don’t do that.”

Yes, we’ve finally got a George in school. He’s a cheeky little chap, who often does things he shouldn’t, so it was only a matter of time before one of us uttered the words made famous by British comedienne Joyce Grenfell: “George, don’t do that.” Why do I wish I’d never said it? Well, for a start, it’s a pretty useless instruction for a child with learning difficulties. The only good thing about it is that it starts with the child’s name, getting his attention. But it isn’t specific. Don’t do what? Sit on your chair? Giggle? Kick Natalie? George was doing all those things at the time. So, “George, don’t kick Natalie” would have been better, but still not good.

Another problem with this instruction is that it uses a negative, which is difficult for many children, especially those with learning difficulties, to understand. Children just beginning to understand spoken words will often pick out key words, as you and I would if learning a foreign language. George may well have heard “George, kick Natalie”, which, of course, reinforces the behaviour. I wish I could get his bus escort to understand this. She greets him with: “I hope you’re not going to kick me again George, do you hear? No kicking. He’s such a pickle, always kicking me.” You can guess the first thing George does every time he sees her. And she has the sore ankles to prove it. So a better instruction might be:

“George, put your feet on the floor!” followed up with a quick “Good sitting!” if he does so.

I’ve learned to be careful what I say to the children. The language has to be precise, and sometimes backed up with pictures, symbols, signs and objects. It’s no good rambling on, using puns or words with double meanings, and you have to be careful with figures of speech. I remember asking Rupert, who has autistic spectrum disorder, to wipe his feet as he came in from play, and guess what he did? Took his shoes and socks off and wiped his feet. Another child responded to: “Are you ready for some dinner in your tummy?” by putting his dinner on his tummy. He’d understood the nouns but not the preposition.

So back to young George. I’ll do my best not to repeat the Joyce Grenfell instruction, but even with my practised language skills, things don’t always go to plan. I remember spending a long time with Kyle, who was about eight, with quite good comprehension skills and a passion for biting people - evidently just for fun, because he got such a good reaction from his victims. I told him that teeth were for biting food, not our friends, and that people felt hurt and sad when he bit them. “Do you understand?” Kyle nodded solemnly and, looking straight into my eyes, stamped as hard as he could on my foot.

Oh well, my mistake again. You live and learn, as they say or, in my case, just live, because I heard myself saying, before I could stop myself:

“Kyle, don’t do that!”

Maria Corby is deputy head of a special school for pupils with severe and multiple learning difficulties. She writes under a pseudonym