A few years ago I was required to ask people whether they’d like to see Tony Blair as prime minister again.

A lot of the responses were, unexpectedly, quite positive. But the one that stuck most in my mind was that of a woman who looked to be in her 50s.

“Who?” she asked. “Is he a singer?”

“No, he was prime minister for 10 years,” I explained.

“Oh, I wouldn’t know about that,” she replied.

It was surprising but also quite depressing. I couldn’t see how she’d managed to avoid the general elections of 1997, 2001 and 2005. Did she never catch five minutes of the news while waiting for Geordie Shore , The Only Way Is Essex or The Jeremy Kyle Show ?

If she’d been a young teenager it might have been understandable. But I felt she was too old to be so clueless.

A difference in generations is how armed forces charity SSAFA is explaining the findings of it survey.

It has discovered that millennials - those who came of age around the start of this century - know far less about the world wars than their forebears from Generation X or the Baby Boomers.

One in five millennials, they discovered, thought we fought France during World War One, and almost half believe Winston Churchill was prime minister at the time. Bewilderingly, one in 10 thought it was Margaret Thatcher.

Three quarters of millennials didn’t know that George V was king at the time, and 16 per cent thought the attack on Pearl Harbor was part of it.

You have to worry about the seven per cent who thought the Battle of Hastings took place during it and the four per cent who thought it featured the Great Fire of London.

Baby Boomers and Generation X-ers, according to the survey, seemed far better informed, and SSAFA director Justin Baynes thought that was only natural.

“Millennials are the first generation who may not have known a family member who fought in World War One, so it’s not surprising that there may be a lack of knowledge about the war,” he said.

I don’t know of any family members who fought in World War One. There was no wartime conscription in Northern Ireland but many people volunteered and two of my great uncles served in the RAF during World War Two.

Yet they never told me about it and anything I know I absorbed through school, TV documentaries, books and generally being alive.

I’m pretty sure most of what I know now about the world wars I knew when I was 21. The millennials have no excuse.

Yet cluelessness does seem widespread among other generations. Private Eye magazine has long chronicled examples of public stupidity in its Dumb Britain column, featuring gems from quiz shows.

On Radio 1 Sara Cox asked: “Beauty is in the eye of the…”

The contestant replied: “Tiger.”

She asked someone else: “What was Bram Stoker's most famous creation?”

“Branston Pickle,” came the reply.

And on BBC 2’s Beg, Borrow or Steal , Jamie Theakston asked the challenging question: “Where do you think Cambridge University is?”

The contestant replied: “Geography isn't my strong point.”

“There's a clue in the title,” said Jamie.

“Leicester,” said the contestant.

If you didn’t laugh you’d cry.

Maybe these people weren’t paying much attention in school - though none of my teachers ever felt the need to explain to us that Cambridge University was in Cambridge.

And even conscientious students can find their attention wandering off the subject. The reason I never figured out simultaneous equations was that I was beginning to find maths less interesting than girls.

But a reasonably good general knowledge is important, whether it’s knowing who Tony Blair was, that Bram Stoker wrote Dracul a and that the Battle of Hastings was rather earlier than World War One.

It doesn’t just help in the pub quiz. I don’t think it’s any exaggeration to say that it can help you make better decisions in life.

You’re better equipped to deal with the present and predict the future if you have some background knowledge of the past, and can compare and contrast situations.

An understanding of the world around us makes us more tolerant of people of different cultures, religions or nationalities. Is that why more graduates voted to remain in the EU?

Any prospective employer will prefer an interview candidate who has some knowledge of the industry and of current affairs.

I suspect it can make you more attractive to the opposite sex too. I’ve met enough pretty airheads to know that a brain is often someone’s most attractive feature.