A sort of homecoming: Boris Johnson hits NYC

Boris Johnson is breaking America. Or at least, he's promoting his new book there: Johnson's Life of London was published in the US last week, and on Wednesday evening the Mayor of London appeared as a guest on The Late Show with David Letterman.

During his interview, Johnson told the chatshow host that he regretted his vow not to run for a third mayoral term; described the capital's bike-hire system as "a Communist scheme"; claimed Londoners were less overweight than New Yorkers; and extolled the virtues of the reborn Routemaster bus – all to the charmed delight of the studio audience.

Letterman got the night's biggest laugh when he asked the Mayor – who was born in New York – how long he'd been "cutting [his] own hair". Americans are just becoming accustomed to Johnson, so they're still cracking the jokes about his hair and bumbling persona that once pursued him in Britain, before it became apparent that beneath the blonde thatch was a formidable, ferociously ambitious political operator. In a brief exchange with The New York Times, Johnson was again asked about hair and buses.

Like his book, Johnson's US tour can reasonably be explained as a publicity exercise on behalf of London. The trip does, however, have the added benefit of introducing the mayor to America, on the off chance that he might someday return as Prime Minister. Both Letterman and the New York Times asked about his leadership prospects, and Johnson gave each of them a variation on his customary response: that he had more chance of being "reincarnated as an olive", "decapitated by a frisbee" or "blinded by a champagne cork". Given the circles he moves in, of course, the latter circumstance is not entirely statistically implausible.