The left-wing anti-Semitism 20th-century Marxists endorsed was not so different from far-Right anti-Semitism. The conspiracy theories and the obsessions about a tiny group of people were the same. But when the magnificent German socialist August Bebel first denounced his comrades for falling for the "socialism of fools" in the early 20th century — "Der Antisemitismus ist der Sozialismus der dummen Kerle" — he was defining a phenomenon that to this day allows leftists to make tactical alliances that fascist groups rarely consider. First, and most obviously in the 21st century, Livingstone and all those like him want to shuffle away from the anti-racism they once professed. If Jews are Nazis or the collaborators of Nazis, then they have no claim on left-wing sympathies. It pleases them, too, to turn Israel into a state created by the Nazis' stooges rather than the victims of fascism. But the point  that hardly anyone notices is that Jews are not the only victims of the Left's double standards. Most pertinently and most disgracefully, der Sozialismus der dummen Kerle allows liberals and leftists, who in normal circumstances deplore the smallest breach of anti-sexist or anti-racist etiquette, to ignore those in immigrant communities and Muslim-majority countries who want the rights that they take for granted and ally themselves instead with life-denying, freedom-hating misogynists, homophobes and racists.

True to form, Livingstone presents Yusuf al-Qaradawi, spiritual guide for the Muslim Brotherhood, as a man attempting to "reconcile Islam with democracy and human rights, in particular women's rights". He does not mention Qaradawi's fatwas in favour of the genital mutilation of girls, wife-beating, and the murder of gays, Jews and apostates. Nor does he discuss why a supposedly left-wing leader is "engaging" with the front organisations for Jamaat-e-Islami, a group that Bangladeshi liberals and leftists see in much the same way as British liberals and leftists regard the BNP. Worse, in fact. For, say what you will about the BNP, no one has accused its leaders of committing war crimes. The leaders of Jamaat, on the other hand, are facing charges of aiding and abetting the Pakistani army's massacres of civilians during Bangladesh's war of independence.

Livingstone is justifiably proud that he faced down the hatred of the right-wing press when he stood up for the rights of women, blacks and gays in the 1980s. This book confirms what we already knew: he is now prepared to forsake his best instincts and ally himself with Islamist clerics who make the Mail hacks of the Thatcher era seem like pussycats. In the process the self-appointed tribune of the Left turns his back on all the Bengalis, Punjabis, Indians, Arabs and Iranians in London who want to enjoy the liberties Britain offers without being menaced by the supporters of religious reaction.