So now we all know that the Labour party - "Her Majesty's Most Loyal Opposition" - has a Jewish problem. Or rather, a problem with Jews. Not just with Israel. Nor with Zionists. But with Jews.

I can tell you, as someone who has devoted practically his life to the study of British politics, that all mainstream parties in the UK have, at one time or another, had a problem with Jews. I can also tell you that this problem survived the Nazi Holocaust intact. Indeed, the disease of a home-grown, thoroughly British antisemitism emerged from that trauma with renewed vigour.

The British people as a whole were, of course, shocked by Richard Dimbleby's harrowing broadcast from Belsen, which the British army had liberated. But if, it was discreetly asked, such terrible things had happened to the Jews, might the Jews themselves be to blame, at least in some measure, for the fate that had befallen them? Did Jews, by their existence or behaviour, actually trigger the prejudice of which they were the victims?

If you add to this outlook, the history of the last, bloody years of the Palestine Mandate, and bear in mind as you do so the triumphant, socialist-inspired anti-colonial mindset that was rampant in the Britain in which I grew up (and which greeted the re-establishment of a Jewish nation-state with scarcely concealed disgust) 60 or so years ago, you're well on your way to understanding how it could have come about that antisemitism survived the Holocaust undamaged, re-energised.

What is to be done? Does history have a lesson for us? I believe it may do.

If Labour is serious, it needs to engage with grassroots

In the 1950s, a scandal erupted in the heartland of Jewish north-west London. It emerged that local golf clubs, the executives of which happened to be prominent local Tories, were cheerfully implementing a policy of excluding Jews from membership.

When the young Margaret Thatcher was adopted as the Conservative parliamentary candidate for the Finchley constituency in April, 1958, she acted swiftly to remove from office in the local Tory party these particular local Tories, no matter how prominent or influential they might have been or might have considered themselves to be.

It was a tough decision for the young Thatcher to take. But she did not hesitate to take it. Does Jeremy Corbyn have the guts to follow her example?

Corbyn apparently knows that the suspension of a Labour councillor here, or a fellow Labour MP there, will simply not do. A handful of token suspensions (followed, perhaps, by one or two high-profile expulsions) is tantamount to no more than treating the symptoms, not the disease itself.

Nor is setting up an inquiry, or drafting a code of conduct, likely to suffice.

Take the case of Bradford West, the constituency that elected Naz Shah as its Labour MP last year. It's now common knowledge that, in 2014, Shah had used her Facebook page to advocate the transportation of Israelis (she can only have meant Israeli Jews) to the USA. Did the rank-and-file membership of the constituency not know this? It now transpires that as an MP Shah hired as a parliamentary aide a councillor (Mohammed Shabbir) who, also in 2014, posted antisemitic remarks on Twitter.

These facts suggest that the entire membership of the Bradford West constituency Labour party needs to be investigated. Then we need to consider the parliamentary constituency of Ealing, where Dr Rupa Huq was elected Labour MP in 2015. Speaking on BBC Radio 4's Today programme, Huq actually mounted a cack-handed defence of Shah. She has now clarified - on Russia Today - that she was simply unprepared for the BBC interview. If so, why, not being fully briefed, did she agree to the interview in the first place? What does her constituency Labour party have to say about this?

If the Labour leadership is serious about confronting anti-Jewish prejudice in Labour's ranks, it needs to dig deep into the grassroots. I suspect that the ideological home for a significant number of Labour members is the Respect party, which advocates the dissolution of the Jewish state and its absorption within what it describes as "a democratic bi-national … state from the Jordan River to the Mediterranean Sea." As for Corbyn, he should demand that every Labour party member accepts the legitimacy of Israel as a Jewish state. If he can't do that he brands himself unfit to lead Her Majesty's Most Loyal Opposition.