Their hijacking of antisemitism, though very successful in setting the media's agenda, hasn't cut through to the wider public. That's because allegations that Labour is institutionally antisemitic, or that Corbyn himself is a racist, cut against, rather than with, the grain of what people already suspect to be true. Those who dislike Corbyn overwhelmingly think he's a politically correct peacenik, not a Jew-hater.

So why stick with it? For some people, no doubt, Corbyn's criticisms of Zionism make him an antisemite. That isn't, I suspect, what is driving the Labour Right. I think they like it because it confuses and demoralises the Left. It may not cut through to the public, but it cuts through to the Left's anti-racist conscience. Because we're not cynical about racism, in the way that someone who suggests putting white people at the head of the housing queue is, we're easier to troll on the subject. It also acts on submerged strategic disagreements on the Left. It's easy to be a happy family when things are going well. But hard choices and difficult, nuanced arguments flush out division. It reveals where the ideologically harder and softer parts of the opposition are, and it gets them arguing among themselves.

For the Labour Right, it also supplies the missing sense of moral purpose. Their polemics have tended to look flaccid, stale, or moon-bound over the last few years. Communism has no place in the Labour Party? Hardly electrifying. On this issue, however, they can achieve moments of superficially impressive indignation. Tony Blair once commented on the difference between himself and the activist Left. The latter being the protesters, the ones who say, "let's get that bastard out of power". As he went on to muse, "I'm the bastard". Well, just for a moment, the hard, cynical political operators who spent their whole lives training to be the bastard, can say, "let's get that bastard out of power". Frank Field, Gordon Brown, Margaret Hodge, the Kinnocks. They know where the bodies are buried, but for the moment they can adopt the style of the campus SJW activist. It's quite animating (take it from an ex-Trotskyist), but totally unsustainable for that tendency.