In order to assess the impact of the antisemitism controversy on the election result, two questions must be answered. They appear to be the same but are, in fact, different.

First, did the issue matter? Second, did it directly affect the result? My answer is definitely yes to the first question but probably no to the second.

Start with evidence about the direct impact. When the Chief Rabbi said Jeremy Corbyn was unfit for office, and virtually every media outlet reported Corbyn’s repeated refusal to apologise to the Jewish community, I watched for a dip In Labour’s support in the opinion polls.

There was none. Labour averaged 33 per cent beforehand and 33 per cent afterwards – and, indeed, 33 per cent on election day two weeks later.

Britain’s two most Jewish constituencies sent conflicting signals. In Finchley and Golders Green, where Labour had come a close second in 2017, Labour’s share of the vote crashed by 20 percentage points, from 44 to 24 points; its candidate, Ross Houston, came third.

But this was where Luciana Berger, one of Labour’s high-profile Jewish MPs who had left the party over anti-Semitism, was the Liberal Democrat candidate.

She also benefitted from the support of most tactical voting websites, and polling evidence that she had overtaken Houston early in the campaign.

Next door, in Hendon, the story was different. Another seat where Labour came a close second in 2017, its candidate this time, David Pinto-Duschinsky, comfortably retained second place.

His vote share fell by just five points to 41 per cent – slightly less than the six-point fall that Labour candidates experienced on average across London.

Those figures, however, do not tell the whole story. The anti-Semitism controversy did not erupt in mid-campaign out of the blue. It had been simmering for years, and with increasing ferocity in the early months of this year.

Had it already deprived Labour of support before the election was called?

This is hard to prove or disprove. What we can say is that Labour’s – and specifically Corbyn’s – approach to the subject appalled many traditional Labour voters; and it almost certainly reinforced the view of most of the electorate that Labour’s leader should never become Prime Minister.

Evidence that the public, and many Labour voters, noticed Corbyn’s behaviour comes from two Deltapoll surveys conducted during the final week of the election campaign, one of the general public for the Jewish Leadership Council, the other of those who stayed loyal to the Labour Party and those who defected, questioned on behalf of Tony Blair’s Global Institute.

These were the proportions saying that Jeremy Corbyn is antisemitic:

General public: 39 per cent (24 per cent think Corbyn and “some elements” of the wider Labour Party are antisemitic, while 15 per cent accuse Corbyn but not the wider party of antisemitism)

2017 Labour voters who defected in 2019: 42 per cent (29 per cent Corbyn and the party; 13 per cent Corbyn but not the party)

Labour voters in both 2017 and 2019: 25 per cent (10 per cent, 15 per cent)

It’s clear from those figures that antisemitism was a huge problem for Labour – and that around 2.5 million people voted for the party despite Corbyn’s stance. (This is consistent with other findings from Deltapoll’s survey: between one quarter and one-third of Labour’s voters comprised people who rejected a great many of Corbyn’s views, but stuck by their tribe.)

What, though, of the 42 per cent of Labour defectors who considered Corbyn to be antisemitic? This figure should alarm the party – as should the 52 per cent who think the current Labour Party is incompetent, 43 per cent who think Corbyn is unpatriotic and 60 per cent who distrust Labour’s ability to spend public money wisely.

This brings to the heart of the matter. The controversy over antisemitism did not take place in isolation of other issues. For millions of women and men, including a great many traditional Labour supporters, it was one of a range of factors that, together, made the party and its leader unbearably toxic.

Stamping out antisemitism will not on its own revive Labour’s support. It is not a sufficient condition for Labour’s recovery; but it is certainly a necessary condition.

Peter Kellner is a journalist and former president of pollsters YouGov