There are "quite a lot of different Lefts," says Rich, "and there are still a lot of people on the Left who want to combat anti-Semitism. I don't think we should concede the idea that the 'Stop the War' Left and the Momentum [Jeremy Corbyn's inner circle activists] Left is the only true Left, and that anyone else is a right-winger. That's the insult they use. There is an assumption of bad faith and dishonesty on all sides."

Rich's bottom line, however, is that extreme anti-Israel advocacy and rhetoric "will always impact on British Jews in a way that is anti-Semitic." It is definitely the case, he writes, "that some on the Left do not recognize anti-Semitism even when it comes from their own mouths."

And he adds that Labour is going to have to decide how — and if — to win back disaffected Jews, whose relationship with the party has "collapsed" in the past 12 months.

"I'm fed up with hearing Jeremy Corbyn saying he condemns all forms of anti-Semitism and then not seeing any action," Rich says. "Commissioning a fairly superficial report [the Chakrabarti report] and then not really implementing any of its findings, doesn't count.

"A charitable interpretation is that they [Corbyn's inner circle] just don't get it," he says. "A cynical interpretation is that they get it, and they find it quite useful. I don't feel in a position to say which of those interpretations is correct."

The Left's Jewish problem