However cliched, the question that crosses every parent’s lips regularly is: “What would you like to be when you grow up?”

With his limited experience of the world, my five year-old son has three options: a racing car driver, a teacher, or one of the Mr Men. While driving to the shops last week, we saw a speeding police car, sirens blaring.

“Why do police cars drive like that?” he asked. “Well son, it’s because they may need to get to an emergency quickly to catch some burglars,” I replied.

“No, that’s not it”. He paused comically; “They just like showing off.”

A stand-up comedian in the making.

Careers advice is something that is rarely discussed at primary school. It used to happen at the end of secondary school, when you went for an interview and someone would enter lots of details into a computer.

In my case, it churned away for a full 15 minutes before informing me that I should become a forester. I don’t know what it was in my answers that suggested I should be miles from civilisation with only an axe for company. I chose primary school teaching.

Is it possible to tell the future career path of someone before the age of 11? I understand the Government is trying to encourage secondary-age children to become army cadets. Why leave out the younger ones? Year 2s are small enough to crawl under barbed wire and immune to shouted orders. I will admit, though, that they are useless under live gunfire.

Primary teachers often tend to draw straightforward conclusions based on aptitude. Good at science? The pupil will be a scientist. Good at history? A historian. Good at geography? The pupil will grow up to be a real-ale bore.

Every school has some pupils in the youth side of a professional football team, spending every spare minute training in the park. Most of these boys will end up in the same place - disappointed when dropped at 14 years old. You may have female pupils whose ambition is to be a footballer’s wife.

Your class may have one of those quiet, intense types who will end up becoming a dotcom millionaire; although canny teachers will stay on the right side of them in case they come back to scale the school clocktower with a high-powered rifle (“I did NOT cheat on that literacy keywords test, Mr Walpole”).

For most adults, growing old is marked by finally understanding what those euphemistic adts on TV for “feminine products” are really for. Teachers have the added problem of being confronted by former pupils, last seen when they were 10, reaching working age. There is nothing more depressing than being greeted by an “Alright, Sir?” from the Sainsbury’s checkout. Where did my youth go?

More from Henry in a fortnight.