Recently, I had lunch with a friend from our Army days. We agreed that the only people who want National Service back are the ones who never did it.

“It may have introduced 18-year-olds to the notion of discipline,” said my friend, “but it also introduced them to the delights of alcoholic poisoning and sexually transmitted diseases.”

At the same time, it did mean that we had a generation of teachers who had experienced a break in the plod from school to college and back to school, that was more of a shock to the system than a few months of Far Eastern backpacking with a group of social contemporaries.

That’s so important. Why do I still hold as role models so many of my own teachers? Because they had been to places and done things that gave them a rare sense of what was important in life. Rudy Wessely, at 14, had been on one of the last trainloads of Jewish children to emerge from the Third Reich in 1939. His parents perished in Auschwitz. He arrived with no English but, 10 years later, he had a maths degree and was my form teacher in a West Riding grammar school.

Sam Hemingfield had piloted a Halifax in Bomber Command. Harry Birkby had flown a glider-towing Dakota to D-Day, Arnhem and the Rhine Crossing.

Arthur Shirtcliffe helped plan the much-dreaded final assault on the Japanese mainland pre-empted by Hiroshima, Nagasaki and the surrender. All had a palpable relish for living that is difficult to emulate when you haven’t done much of it.

But what’s the point of this? You can’t rewind your personal history and join the SAS at 17 instead of doing a Saturday job in Tesco, can you? No.

But what you can do is try hard to cling on to and develop a life outside school, something absorbing and entirely different from your classroom.

One of the most contented and fulfilled teachers I know is a Salvation Army member. Another spends several evenings as a volunteer in a residential home for people with disabilities. Yet another spent two years developing art education in the Caribbean, an experience that’s left visible traces on her family’s lifestyle. And in that regard I see that Voluntary Service Overseas is actively recruiting experienced teachers to help in training colleagues in the developing world. Not a bad alternative, I’d say, to doing a secondment as a literacy strategy consultant.