It is understandable that, with the destiny of our nation at stake, almost all political and media attention has been focused on Brexit. As a consequence, a number of developments in Labour’s antisemitism crisis that would ordinarily have been at the centre of the news agenda have been ignored.

This week, for example, it was revealed that Labour MP Chris Williamson was greeted in the House of Commons chamber by Jeremy Corbyn after his suspension with a pat on the shoulder and a cheery “comrade”.

The insincerity of the Labour leader’s claim to be determined to stamp out antisemitism is so blatant that he might as well have his fingers crossed behind his back when he speaks.

This week’s JC — as every week — is full of examples of Labour antisemitism that, had they been the first to have emerged, would have prompted astonishment. But they are now so regular that they barely produce a raised eyebrow.

Before Mr Corbyn became Labour leader it would have been inconceivable to have felt any need to ask Jewish voters whether antisemitism is an important factor in deciding how they would vote.

But today, because Labour is led by an antisemite and is regarded as institutionally antisemitic, not only is the question vital, 96 per cent of British Jews say that it is indeed important.

This is where Brexit comes in. Such is the political chaos that an election is far from impossible, with the possibility — likelihood, even — of a Labour government following, with an antisemitic Prime Minister buttressed by an institutionally antisemitic party. Which is why all decent Labour MPs must now — not at some indeterminate date in the future, but now — decide if they can remain.

While they stay, they are the enablers of antisemitism. If they cannot have that on their conscience, they know what they must do.