Johnson had changed the result of a national poll, and become a feared and admired writer. Not bad for a journalist still in his twenties. But you can make a convincing case that his private convictions were one thing and his public poses quite another. His father was an EU bureaucrat who brought up Johnson among the Brussels salariat. David Usborne, the Independent's man in Brussels at the time, said, "I always assumed he didn't believe that stuff. He could do. But he played the Telegraph game brilliantly [and] compromised his intellectual integrity to get on. I assume that he has done that in the rest of his career."

When he entered parliament in 2001, Johnson was a liberal rather than a right-wing  Conservative. Chris Cook, an aide to David Willetts, told Purnell: "He was clearly not on the right wing, but actually quite europhile in Tory terms. He liked to come into our office to gossip and bitch about the right-wingers he thought had screwed up the party." Johnson ran from the Left to beat Livingstone in the mayoral race of 2008. In power, he advocated granting an amnesty to half a million illegal immigrants —a policy Conservatives reviled when the Liberal Democrats proposed it during the 2010 general election, while quietly forgetting that their own standard-bearer in London supported it too. Johnson's London has not been noticeably different from Livingstone's London. He has been as keen on vanity projects as Livingstone was, and focuses on the centre of town at the expense of the outer boroughs just as obsessively as his predecessor did.

As revealing as the shifts in policy is his power-worship. Throughout his career, Johnson has looked for men who could help him. He has treated them with the necessary servility and then dropped them when they could no longer serve his purpose. When Conrad Black was a media mogul and in a position to give him the editorship of the Spectator, Johnson never allowed a word of criticism to pass his lips. The moment that a financial scandal engulfed Black, Johnson turned on his former patron. He ran a piece by Peter Oborne denouncing Black for his "stolidity, clumsiness and provincialism", "hairy knuckles and paddle-like hands" and "fondness for ceremony and dressing up that was pre-modern in its profound lack of irony and unabashed vulgarity".

Like many others on the Left, I criticised Black when he was in his pride and pomp, although I hope with slightly more elegance than Johnson and Oborne managed. The difference between them and us is that left-wingers did not take Black's money, flatter him to his face, accept his promotions, break bread at his table, laugh at his jokes and reject him only at the moment of his disgrace when he could no longer offer us preferment. We at least understood that it is one thing to criticise a man when he is on the up and another to kick him when he is down — a distinction they apparently no longer teach on the playing fields of Eton.