Forget the baggy silk shorts with the dragon motif on the front; what sportswear the Mayor of London chooses for his morning jog should be no concern of ours. What is more intriguing is the mismatched socks: one dark, the other pale. When I saw that photo of Boris jogging in them I thought: that has to be deliberate. An affectation. Not even he would put on mismatching socks by mistake.

For a moment it made me see him in a new light. If there was calculation behind the socks, could there also be calculation behind the unkempt hair, the vague and distracted manner, the Wodehousian language? Does he come down stairs in the morning with his hair neatly combed, looking immaculate in a suit, and then “step into character” before opening the front door? Tie askew? Check. Hair ruffled? Check. Latin phrase that few will understand? Damnant quod non intelligunt.

That voters find this “Boris” persona endearing is not in doubt. We like people who don’t care about their appearance. It is the opposite of vanity. But I don’t think it is calculation in his case. I reckon he did notice that he was wearing odd socks but he simply didn’t care enough to go back and change them. The contrast with David Cameron is telling. If Boris takes no care, Cameron takes too much. When the Prime Minister is photographed out jogging he has all the latest Lycra kit. And his paranoia about being photographed in tails at the Royal Wedding last year did not reflect well on him.

It was said that there was calculation in Harold Wilson’s man-of the-people Gannex mac, not to mention his pipe. But with certain other politicians I think the trademarks have been genuine. You only need look at the pint-drinking, jazz-loving Kenneth Clarke to know his Hush Puppies are not an affectation. But I think the most revealing parallel in Boris’s case is with Winston Churchill. Boris was born in America. Churchill’s mother was American. Both began their careers as journalists. Both started out as liberals (Boris was an SDP supporter, briefly, at Oxford). Both are known for their wit and their love of quoting verse. Both have deployed bombastic rhetoric for comic effect.

But it is their scruffiness which is most telling. Churchill had terrible, or rather bohemian, dress sense. When in 1943 he arrived in Canada wearing an unbleached linen suit there were gasps. On another occasion he startled troops on a ship by walking around wearing only a flapping dressing gown, without underpants.

On other occasion it was the underpants which caused comment. Field Marshall Lord Alanbrooke noted in his diary that the prime minister favoured pale pink silk ones. They were all he was wearing at one of their meetings. His all-in-one Siren Suit, meanwhile, was made of velvet and was bottle green. As for his bow ties, they were never tied the same two days running: lop-sided, bulky, tiny, perpendicular…
According to Dr David Weeks, who did a definitive study of eccentricity, eccentrics tend to be unembarrassable mavericks. And they have the sort of buoyant positivism that comes from being comfortable in their own skin. They are always possessed of a mischievous sense of humour, are opinionated, quixotic, intelligent and impulsive — and are wont to find unconventional solutions to problems. Isn’t this as good a description of Churchill, and Boris, as you have ever heard?