SOME words are just words. They do their job and everyone moves on. But some words are heavier than that. Some words come with history and weight and significance and should only be used with caution. One of those words is “collaboration”.

The reason we should be careful about that one word in particular is obvious: “collaboration”, and its close friend “collaborator”, come with disturbing images built in. Women in occupied France having their heads shaved because they had relationships with German men. Or someone picking up the phone to tell the authorities about a Jewish family hiding in a building on the Prinsengracht in Amsterdam. The Second World War has loaded the idea of collaboration with dark significance and everyone knows it.

And that includes Boris Johnson. He is the Prime Minister for God’s sake. He has written a book about Churchill. He had an excellent education. He knows the significance of putting a word like collaboration into a sentence, particularly a sentence about Britain and Europe, and yet he did it anyway.

What he said was this: “There is a terrible kind of collaboration as it were going on between those who think they can block Brexit in parliament and our European friends.”

Some people will say the PM was just extemporising and making a general point about Brexit and that the word “collaboration” slipped out. But the idea that he didn’t realise what he was saying, or didn’t mean it, is hard to believe. Mr Johnson’s brain is big enough to work his mouth isn’t it? So, he should have been, and surely was, aware of the significance of the word he chose.

And this is part of a pattern anyway, from Mr Johnson in particular and Brexiters in general. During the European referendum campaign, Mr Johnson drew a parallel between the EU’s aims and Nazi expansionism; he’s also used other controversial words and phrases in the past that have been far too on-point in terms of his electoral aims to be accidental. And it’s hard to forget the Brexiter MP Mark Francois summoning up images of the D-Day beaches in his attack on the German boss of Airbus.

But let’s count the ways in which comments like this are offensive and stupid.

First, using imagery and words from the Second World War is, at best, the tactic of a populist but at worst it’s dabbling in language that’s often used by nationalist extremists. The suggestion is that a country is being “occupied” – it could be the UK by the EU or it could be Scotland by the UK – and you are either an ally of the cause or a collaborator or quisling. We’re not having a constitutional debate; we’re at war. It’s ludicrous.

It also misunderstands what the Second World War was about. Britain was fighting against the threat of occupation, but the politicians that emerged from the conflict set up the UN and the European Coal and Steel Community, the forerunner of the EU. The war wasn’t about anti-Europeanism. Quite the opposite: it was about pro-Europeanism.

And consider what the men and women of the Second World War thought they were fighting about. I know there will be veterans, and sons and daughters of veterans, who voted for Brexit, but I’d like to tell you about the day I met Squadron Leader Nigel Rose, a pilot in the Battle of Britain and a veteran of 602 City of Glasgow Squadron.

Mr Rose was 92 when I met him, but his recall of the war was vivid. He told me about all the little details he remembered: the smell of cordite and soap and grass; the bang of a bullet slicing through the metal of his Spitfire; and he told me about August 18, 1940, the day the clouds cleared and he saw a hundred German planes below him, heading for Britain. He chose his target and swooped down towards it. He was 19: a fighter pilot who’d only just stopped being a boy.

Speaking to Mr Rose that day was a great privilege and something I’ll never forget, but hearing him explain his motivations was particularly interesting. He wasn’t driven by hatred of the Nazis, he said, more a desire to defend the way he lived.

“We take a pretty balanced, liberal attitude to life in this country,” he said, and, as he saw it, he was just a non-extreme person defending a non-extreme life. He then tried to find one word to describe what he was fighting for and he chose “reasonability”. “That’s what it was,” he said. “Life’s too short to hate each other.”

Wouldn’t it be wonderful if Brexiters could see that? They summon up the war in defence of their ideology, but if they read more about the lives of veterans like Nigel Rose, perhaps they’d see that the lessons of the Second World War undermine Brexit rather than support it.

The Prime Minister has accused politicians and voters who oppose Brexit of collaboration. But the truth is that Remainers are campaigning for a set of ideals that applied during the war and still apply now. Co-operation. Anti-extremism. Reasonability.