There are two types of Hitler gaffe. The first is lavishly illustrated by the bungling attempts by Sean Spicer to draw historical parallels between Hitler and Syria's Bashar al-Assad. Even in expert hands, these would have been difficult to trace out in useful or meaningful detail. When Spicer had a go it ended rather predictably, as we have seen.

Spicer was way out of his depth and displayed such insensitivity and breathtaking ignorance as to make him unqualified to be even a mouthpiece for President Donald Trump. He's an idiot but I do believe that, now someone has explained a few of the basics, he is mortified and repentant. He can be rehabilitated; he does not deserve to be vilified for the rest of his life.

I wish I could say the same about Ken Livingstone. His is the second variety of Hitler's gaffe, characterised by a superficial scholarship defiantly adhered to. Which is to say that the perpetrator doesn't think it a gaffe in the sense of being wrong, in any case.

Sean Spicer apologises following his claim that Hitler didn't use chemical weapons

This is a much more insidious phenomenon than Spicer's plain ignorance. I have no great pretensions to being an expert on the Third Reich or hold any novel insights into Hitler's mind, but I do know that brilliant expert historians have laboured for decades and would not ever have pretended to know what Livingstone says he knows about Hitler's intentions, about when he “went mad and murdered six million Jews”, or the motives and circumstances of the Zionist movement's engagement with Hitler's party in opposition or the German government after the Nazis came to power.

This type of gaffe is indeed insidious because it used to influence opinion today in quite a sinister fashion. Even if Livingstone was right about the history, that remark doesn't do anything to move the debate about the Middle East along. At best it was a cheap debating point. In practical terms it makes the Labour Party look institutionally anti-Semitic (which, to be fair, I doubt).

The net practical ironic effect though is to keep Jeremy Corbyn (who, to be fair to him, condemned the remarks), Emily Thornberry and Livingstone himself as far away as can be possible from British foreign policy making.

Labour betrayed Jews by not expelling Ken Livingstone, May says

We have an unhealthy obsession with the past, especially the last war and Adolf Hitler's rise and fall. The “lessons of appeasement” have been misused by everyone from Anthony Eden at Suez to George W Bush in Iraq. George W even had a bust of Churchill in the Oval Office, while Boris Johnson still writes books about him.

The parable of Hitler, Chamberlain, Churchill and appeasement is being trotted out again, even now, over Russia and Putin – also lazily labelled a new Hitler. There are similarities, of course, but huge differences too. When you reflect on how Russia suffered in the war you can see why it is offensive and counterproductive to make the claim.