Has Boris Johnson blown his chances of becoming leader?

Boris Johnson was certainly the cabinet’s most flamboyant figure, as well as its most prominent Brexiteer. And he’s had a difficult few weeks, from his highly visible absence from the vote over the Heathrow expansion, to the four-letter expletive he issued to businesses concerned about the impact of Brexit. He has made no secret of his own leadership ambitions, but has he finally blown his chances?