t’s hard to take the British prime minister, Boris Johnson, completely seriously. Just look at him: a chubby, permanently disheveled toff with an accent that comes off as a parody of an upper-class twit, topped off by that trademark mop of silver-blond hair he deliberately musses up before venturing into the public eye. Then there are those photo-op moments in his long career that seem designed to make him look supremely silly — stuck dangling in midair on a zip line with little Union Jacks waving in his hands; rugby-tackling a 10-year-old in Japan; playing tug-of-war in a publicity stunt and collapsing, suited, onto the grass; or declaring at one point that he was more likely to be “reincarnated as an olive,” “locked in a disused fridge,” or “decapitated by a flying Frisbee” than to become prime minister.
And yet he has. And more than that: This comic figure has somehow managed to find himself at...