There is indeed a record of anti-Semitism in the Labour Party but it is firmly located on the right of the party.
It was Sidney Webb, for example, one of the party’s leading intellectuals, who said that, “French, German and Russian Socialism is Jew-ridden. We, thank heaven, are free.” During the Second World War it was Labour home secretary Herbert Morrison who denied entry into Britain to Jewish refugees fleeing the Nazis. And after the war it was Clement Attlee, the Labour prime minister, who refused to consider Ian Mikardo MP for a junior position in the government because there were already too many of the “Chosen People”. It was the 1945-51 Labour government that refused entry into Britain to Jewish Holocaust survivors while at the same time allowing a surrendered Ukrainian SS division 9,000 strong to settle in the country.
Quite how British reformism has got away with keeping Holocaust survivors out of the country, but allowing in an entire SS Division is a bit of a mystery, certainly something that Labour members seem unable to explain.