Still, I do like them, or most of them. There is also the other side of the equation. Certainly, I am prone to great pink flashes of warmth - as when I think of Baz, who finds schoolwork really puzzling but who explains to me how he has been working hard on his spelling sounds, or of Nesta, a skinny little bit of a girl who is all enormous brown eyes and silky curls, who gets her tongue right out, her hand curled round her ear and her pencil driven along the page with frowning concentration as she writes about Guy Fawkes. But I am also given to nasty little buzzes of irritation or plain old-fashioned dislike.

Take Stephen. Stephen is a little tick. He is bright. He has stick insects at home. He has a science set at home. He does extra maths for fun at home. He has educational birthday parties. His mum is a pillar of the school. All, apparently, well and good. Not yet aged seven, Stephen, wrongly, believes that he knows everything. Pity the poor parent helper, then, who has the task of explaining to him that counting on in twos is not the same as knowing the two-times table and that because even numbers are divisible by two, that does not mean that even numbers ARE the two-times tables. Stephen will not believe me even when I introduce terms like “multiplier” and “multiplicand” (OK OK, but I didn’t go to teachers’ training college).

“Look,” I want to say, thumping my hand on the desk and yelling, “You little nitwit, just take my word for it. One-times-two is two, two-times-two is four, three-times-two is six: that is the two-times table. Two, four, six, eight, ten, are even numbers, yes, they are counting on in twos, yes, but THEY ARE NOT THE TWO-TIMES TABLE, ALL RIGHT!” I don’t do this, of course. I merely smile and go over it again.

This time, even Nesta gets it. I look at Stephen. He is gazing at me with unfathomable eyes. There is a little smile at the corners of his mouth. He is winding me up, I know it. I give him a big, and totally phony, smile. He drops his eyes. I take a deep breath. “I expect you’ll understand it when you are older,” I say, unforgivably. He shoots me a glance of black dislike. Honours even, Stephen.

I bet you are thinking what a wicked woman. But you don’t know what I know. You don’t know how Stephen gets our boy with learning difficulties in the cloakroom and gets him to show his willie - and then speaks disparagingly of it. (“It’s dirty, mine’s better”.) You don’t know how he wraps this same boy’s scarf around his neck and pulls, as a “scientific experiment”. You don’t know - how should you? - how he used to yank Jake’s trousers down and yell out “Fat bot, fat bot”. Or that he likes to pinch people when they are not looking. Or that he jeers at other children when they are crying.

I know these things because I have seen some of them and because the children tell me as we sit on the bench outside at break. And I know because a couple of the mothers tell me, embarr-assed, because they don’t know what to do and they think, because I help in class, I may know what to do. But I don’t. I tell the teacher. She is not surprised. She firms her lips and says she will keep a lookout in class. But Stephen does not do these things in class. He does them slyly, when no one is looking. He does them for fun.

So now, whenever I am prone to gushing pinkly - “They are such a lovely class” - I remember Stephen in the cloakroom and I say instead, “There are some lovely children in that class.” Handsome is as handsome does.