Years ago, when I was about ten, I briefly had a particularly terrible teacher. He was a hateful, poisonous old man, loathed by all his pupils for his spite and malice. I’m not sure how he ended up teaching, and to this day I really don’t understand how he held onto his job.

For a short while, though, I saw another side to him.

When the Falklands War began, he put a big map of the islands up at the bottom of the school stairs. Every morning he’d carefully move little coloured pins across it,...