The former mayor of Jerusalem Teddy Kollek, who died this week, was the quintessential municipal leader. He cleared slums, built houses and made the city greener. So far as I know, he never gave unsolicited advice to the British Government on the constitutional status of Northern Ireland. But if he had done something so presumptuous and futile, he would have been anticipating his present-day London counterpart, Ken Livingstone.

Mr Livingstone is the host of a conference this month entitled “A World Civilisation or a Clash of Civilisations”. His website states: “The view has been put forward that the world is going into an era of conflict and war driven by a clash of civilisations. The Mayor’s policies are based on the exact opposite idea: that the multicultural city is part of creating a new concept of world civilisation that corresponds to a globalised world.”

If this vacuity means anything it must be that a single category of citizenship transcends divisions, and that a cosmopolitan city symbolises that unity. Yet Mr Livingstone’s behaviour undermines the notion. Three weeks after the 7/7 bombings he welcomed to London Yusuf al-Qaradawi, the Muslim cleric who praises suicide attacks in Israel. Mr Livingstone’s exculpation of these comments was that Palestinians have only their bodies with which to “fight back”. Astonishingly Mr Livingstone believes his conference is competent to debate “democratic solutions for the Middle East”.

Mr Livingstone asserts “a responsibility to support the rights of all of London’s diverse communities”. But Londoners are not communities. People belong to groups, but for civic purposes they are citizens who are equals under law. The notion that democratic politics celebrates group identities leads to the absurdity of a left-wing politician literally embracing a leader of theocratic, xenophobic reaction.

The conference’s title is a disparaging allusion to a book by the political scientist Samuel Huntington. Yet Huntington’s ostensibly conservative-realist argument is echoed in the assumptions of the multiculturalist Left. “Western universalism is dangerous to the world, declares Huntington, “because it could lead to a major intercivilisational war.” Only one of the conference’s listed speakers is liable to dissent. Others include an Islamist academic, a pacifist and a representative from George Galloway’s Respect party.

In fairness, I should add that I and another liberal writer scornful of Mr Livingstone’s identity politics received an invitations to speak, apparently as an afterthought, a few days ago. Perhaps the event’s exhortatory character had become too blatant. The conference and its principal figure remain, however, in expense, symbol and sentiment, a substantial net liability for London.

Times Recommends

• Unite workers! You’re in Mr Brown’s pocket
• Obama is bashing on the brick wall of unlogic
• Want to understand the war? Ask the generals