It is in this context that one must place Ken Livingstone and his Zionists = Hitler outburst and Naz Shah’s suggestion (which Mr Livingstone was excusing) that the entire population of Israel should be deported to the United States. Both of them must feel bewildered by the condemnation heaped upon them, because they inhabit a party whose leader has, over his 40 years in politics, spent hundreds and hundreds of hours sharing platforms with virtually every sort of Muslim anti-Semite and advocate of terrorism that one can imagine. They may have thought they had permission.

There is, of course, an important difference between Mr Livingstone and Mr Corbyn. You can tell by the way the former drags Hitler in, by his bad-taste references to hating Jews as if it were half-funny, that he actually is personally anti-Semitic. You can find no such thing, to be the best of my knowledge, about Mr Corbyn.

But I’m not sure that makes things better. If Labour’s problem was individual, oddball anti-Semites, they could simply be removed. If it is about an ideology so wide and deep that its adherents don’t even realise what they are supporting, then you really have got trouble. If perfectly pleasant people like Mr Corbyn, with no personal malice, nevertheless make common cause with such extremism, then you have got, to use a concept beloved of the Left, institutional racism.

This story is less to do with individual wickedness than with what has happened to the Left. The stuff that Mr Livingstone garbled about Hitler supporting Zionism comes from a book by Lenni Brenner called Zionism in the Age of the Dictators. Brenner, a Trotskyite who renounced his own Jewish upbringing, sought to prove that Zionism in the Thirties was a Jewish collaboration with Hitler. In the early Eighties, when the book was published, Mr Livingstone was in charge of Labour Herald, the newspaper vehicle for his hard-Left takeover of London Labour (printed with the help of money from Colonel Gaddafi’s Libya). Labour Herald gave Brenner’s book an ecstatic review. It was part of a growing trend.

During the Sixties, much of the Left moved from its traditional concern with the organised working class to a greater focus on “the wretched of the earth”. The phrase was the title of a book by the Marxist philosopher, Franz Fanon, who heavily influenced, among others, the young Barack Obama. In this picture, the greatest enemy was colonialism, and the perpetual victim was the Third World, or what is nowadays called the Global South. Violent struggle by the victims to cast off their shackles was advocated.

In the same period, the Soviet Union, which had frequently used anti-Semitic propaganda to reinforce its internal repressions, began to export the stuff. In the Middle East, where it sought advantage against the United States and the West, such tropes were particularly effective. Many in the Muslim world craved support for the idea that Israel, which had so amazingly trounced its Arab neighbours when they attacked it in 1967, was part of a global plot by Western power and money to keep them in subjection.

Until then, in countries like Britain, Jews and Israel had usually been well treated by the Left and seen as allies in the fight against fascism. Now this shifted. The Young Liberals, taken over by leftists such as Peter Hain, who much later became a Labour Cabinet Minister, were the first grouping to become militant about the Palestinian cause. Then the ideology spread, and gradually broadened into the all-encompassing account of dispossession and oppression – applicable from Bethlehem to Belfast to Birmingham, Alabama – which it is today.

One might have thought that September 11 2001 would have made this movement pause. If blood-crazed theocrats had started the 21st century by blowing up themselves and a couple of thousand ordinary citizens in the name of Allah, might it not be time for a bit of secular modernity? But no, instead these events seemed only to assist the narrative of burning grievance against the West, and the conspiracy theories that go with it. Many of the chaps and organisations with whom Jeremy Corbyn has shared platforms have ever since promoted the brilliant idea that it was actually the Jews who destroyed the World Trade Centre. I have not heard Mr Corbyn rebuke them for saying this.

Although people like Mr Corbyn have never shown belief in Islamist doctrines about chucking homosexuals off cliffs or imposing sharia law or torching synagogues, they have found themselves absolutely unable to confront such things. In doing so, they would have to question the most sacred tenet of the “anti-imperialist” Left, that the Western powers are always wrong. Besides, why should they consider accusations that they are anti-Semitic? In their minds, anti-Semitism, like all other racism, is a product of fascism. They are anti-fascists, so they simply can’t be racists.

By electing Mr Corbyn as leader, Labour in effect endorsed this paranoid narrative of grievance and conspiracy that has developed over the last 50 years. So its new recruits are drawn from that school of thought – more Islamists and anti-Semites; fewer Jews, or, come to that, ordinary working people. Unlike in the Eighties, the party has not been infiltrated in a calculated manner (though Mr Corbyn’s lieutenants are now making up for lost time). It has simply decayed so much that its immune system can no longer resist the infection. One of our two main parties has adopted, almost without thinking about it, an ideology of which race hate is an intrinsic part. This has never happened before in Britain.

Next week, London will elect a new Mayor. Sadiq Khan, the Labour candidate, is astute. He was quick to condemn Mr Livingstone on Thursday. But he too has done a good deal of platform-sharing. In 2004, for example, he appeared on the same bill in Tooting as prominent Holocaust deniers, Hamas supporters, misogynists and supporters of violence against Israel. He now says he “regrets giving the impression” that he shared their views. The other main performer on the platform that day was a backbench Labour MP, one Jeremy Corbyn. Today, regrets are too late.

http://www.telegraph.co.uk/news/2016/04/29/how-the-labour-party-embraced-an-ideology-that-has-race-hate-at/