I WENT TO a reunion of my old school last year, the first I've been to for 40 years. It came about like this.

In August I received a letter from a man named Ray Hampton who was on holiday in Cheltenham, England. He had been reading a detective story, he said, and he had noticed that half the characters in the book had the names of people he had been to school with, so he looked at the cover and saw that he had been to school with the author, too.

I had been expecting this letter for a few years because there were eight of these books out there now, all of them containing the names of at least one of the boys I knew in Mitcham County School.

When I wrote my first book I had no problem naming the hero, but none of the other names sounded real until I hit on the notion of using the names of my old schoolmates, the ones I liked. Thus Sergeant Gatenby, now retired, got his name not from a well-known Toronto entrepreneur of the arts, as many have assumed, but from old "Blob" Gatenby, a cheerful, chubby kid who used to sit on the left, in front. "Peastick" Churcher, a particular chum, became an English police inspector in another book, followed in the next by a suspect, Tony "Harry" Harold. "Joe" Ockenden had his day as a forger of Canadian art; "Tats" Atterbury, "Chimp" Simpson, "Muggo" Munnings - they are all there somewhere.

When I got the letter from Hampton, I was rather eerily in the middle of a book in which "Hambone" Hampton plays the part of a klutzy police cadet. I wrote back saying how pleased I was to get his letter, and he replied saying that the Old Boys held a reunion every year in a room over a pub off the Strand in the last week of December, and if ever I was in England I should come along. He said that only about 30 or 40 came, because the school had been closed down shortly after we left so the Old Mitchamians was a shrinking society. I should add that it wasn't a very distinguished school; it was about on a level with the one John Major attended, which was in fact in the same district. I might have gone to his, but they wore straw hats in summer that would have cost me my life on my street.

I put the letter away; there was no question of flying across the Atlantic to drink three pints of beer over a pub! But by an amazing stroke of management it turned out that I was needed that week in London to read the proofs of my next book, so on Friday, the 6th of December, I was sitting in a hotel room in Russell Square wondering when to start out and what to expect. I was very nervous. How would I recognize anyone? More to the point, although I had needed only the names, had I by chance chosen them subconsciously because, although I hadn't seen them for 40 years, they seemed right for the parts?

At 5:45 I walked through the door of the upstairs room of the George and a man shouted "Here he is" and I was shaking hands, more or less simultaneously, with three elderly men, grinning like fools. Within minutes, I had identified Peastick Churcher and even managed to call him Bert, which I had never done before.

Hambone was there; Joe Ockenden wasn't but his younger brother, Little Joe, was, and there in a comer were Glover and Dawson.

Half an hour after that, three 15 -year old boys - me, Hambone, and Peastick - were drinking beer, remembering, and I had relaxed. No one had really changed, and there was no connection at all between these people and the names I had used. It's true that Hambone had been a brilliant soccer player, and 1, who had desperately wanted to be, had been no good at all, but surely that had nothing to do with my making him a klutzy police cadet? Only my psychiatrist would know for sure. True, too, that Peastick could have passed for a police inspector, but the real, witty Peastick, who had once made fun of my first long trousers, was nothing like the stolid, humourless character in my book.

Hambone, Peastick, and I were the last to leave. I had had a wonderful time and got everything I came for, but the next day Hambone called my hotel saying it wasn't enough, so the three of us met again in a West End restaurant on Monday night and had another fine evening, getting down to remembering all the slights we had suffered as scholarship boys with the wrong accents at a grammar school.

At 10 o'clock we were walking across Leicester Square to the tube station when we ran into a huge, oddly dressed crowd. I recognized them immediately from Toronto's own Halloween parade - it was a convention of transvestites, a lot of hairy fellows dressed up as beauty queens.

It was easy to see through their disguises.

But no one could have known that among the onlookers was a little gang of 15-year-old boys dressed up in the clothes and wearing the face-masks of three elderly gents on a night out, and that two of them had once dressed up as policemen.