Nick Cohen, a journalist with impeccable left-wing credentials, has written a book about the latest moral disorder afflicting his brothers and sisters in the struggle. Fashionable anti-Americanism and hatred of the Bush administration and Tony Blair has so warped opponents of the war in Iraq, he argues, that they want the Islamic terrorists to win.

In What’s Left? How Liberals Lost Their Way, Cohen asks, “Why do leftist papers publish defences of suicide bombers?” and answers that the failure of socialism has freed them to go along with any movement, however far right it may be, “as long as it is against the status quo and America”.

The triumph of liberal-left social agenda in the West, and Britain in particular (human rights, gay rights, women’s emancipation, etc) left a gaping black hole to be filled. But these causes are, apparently, not for export. “They could all be for the emancipation of women in London, Paris and New York while indifferent to the misogynies of the Middle East, Africa and Asia,” he writes. Supporting these values in the Second or Third World is moral imperialism, don’t you know.

What’s Left? has created havoc among the Guardian-reading classes. It asserts a commonality of interest between the hard left and soft liberals who lazily take up the arguments of their malevolent brethren. For those not of the faith, it offers a defence of the alliance of the liberal interventionist left with American, and British military power in the Balkans, Sierra Leone and now, fatefully Iraq. Neo- liberals as well as neocons thought they had found the philosopher’s stone of foreign policy, an idealism grounded in realism. For a decade they swept all before them until Abu Ghraib and Baghdad, city of dreadful night, brought them up short.

At Cohen’s invitation we meet in a pub in Islington where George Orwell, his intellectual hero and forerunner, once lived. It’s not exactly his imaginary perfect prole boozer, the Moon under Water — for a start an effete, all-male Swan Lake ballet has been showing at Sadler’s Wells next door. Orwell, that fierce inverted snob, would also have sneered at our teetotal, bourgeois consumption of pints of orange juice and lemonade. Indeed, we rather despised ourselves for it too.

Tall, gangly and a voluble, entertaining talker, Cohen fires machinegun rounds of invective when I ask him about the reaction from his tribe. “Serious people on the left I have no trouble with. They may not agree with me but they know something is going wrong. An Oxford don has told me, ‘I’m against the war but I hate going on a demo with anti-semites and Trotskyites’. It’s the soft left liberal intelligentsia, those bloody comedians we get these days — they want to feel righteous, they dislike all ambiguity. They want to think they are good. They swear at me.”

Auntie gets it on the chin too. “I support the BBC but I think our problem is the concentration of media in London. When there is an absolute liberal consensus, everyone they meet, eat or sleep with thinks the same damn thing.” So in Iraq’s case this groupthink didn’t come in the hard questions they asked the other side, but the soft questions they asked their own side. “For years,” he writes, “the BBC’s attack dog presenters couldn’t manage to give one opponent of the war a tough interview. Not even George Galloway.”

Auntie got her “impartial, balanced” revenge; on Radio 4’s Start the Week last Monday Cohen was politely monstered by every other left-liberal guest. The Guardian also came up with a novel way of pigeonholing Cohen’s politics as unworthy of serious discussion. “The Guardian online talkboards carried a discussion with me and another supporter of the war from the left with a Jewish name, which was entitled: ‘David Aaronovitch and Nick Cohen Are Enough to Make a Good Man Anti-Semitic’.” Not funny, not clever. He has also been pilloried on the paper’s op-ed pages by an apologist for the communist dictatorship in Cuba.

There it is, that surname (he isn’t Jewish) seems to be enough to damn him in some quarters, although he supports a Palestinian state and peace based on United Nations Resolution 247’s famous call for a return to something like the pre-six day war borders. Because Cohen wonders why the left doesn’t devote anything like the same attention to, say, Robert Mugabe’s Zimbabwe as Israel, he is presented in some quarters as a stooge of the American neocons and their right-wing Israeli Likud party allies.

Worse still for a leftie is that righties have been talking him up. “I wasn’t thinking about it while I was writing. You can’t have one eye over your shoulder thinking Michael Portillo will like this and my left-wing friend will hate that.” In fact Portillo does sympathise with Cohen. But for different reasons. His personal journey is a mirror image of Cohen’s — he upset the shibboleths of his Tory tribe and has been treated by some as a heretic fit for the stake. “He put a friendly hand on my shoulder and was kind,” Cohen says of one encounter.

His former editor at the New Statesman, Peter Wilby, wrote an editorial claiming that the Americans had it coming to them over 9/11, because “they preferred George W Bush to both Al Gore and Ralph Nader. These are harsh judgments but we live in harsh times”. How do they manage to talk? Cohen will only say gently: “Peter and I have been friends for a very long time.”

What does his poor mother, a stalwart of the Labour party, think about the book? After all Cohen’s leftist Manchester parents were always on the march against fascism or some other evil of modern capitalism. With his fine eye for comedy as well as polemic, Cohen recounts how his mother “searched the supermarkets for politically reputable fruit”. Oranges from Spain were out because of Franco, ditto ones from the Algarve as Portugal languished under Salazar. Outspan from South Africa was no go, of course, because of apartheid. Florida or Jaffa oranges were evil because of Nixon and the Israeli occupation of the West Bank.

Times Recommends

• Should Knox’s trial even have reached the courtroom?
• All that glitters is not sold in Wright’s world
• Believe it or not, Big Brother is your friend