Why and how has this remarkable thing happened? Quite simply, Cameron - with or without a druggy past - has media appeal. He is easy on the lens. He looks good, in fact rather like Tony Blair did in his late thirties.
He sounds good, though perhaps a tad too posh. He needs to mangle a vowel or two. He comes across as genuine, friendly, a listener, a joiner-in but with a real backbone and some firepower in reserve. He is articulate.
A 15-minute speech without notes in front of the party faithful and the world's media would turn most politicians to jelly. The man is brave and self-confident without appearing arrogant.
He looks like a leader too. Striding out of Parliament with his coterie of supporters wedged in behind him, he has a Pied Piper look to him.
How have I, and it seems many others, come to this view given I had never heard of Cameron until September? The answer is, of course, that the media have driven a short-cut through my impression-building apparatus. TV, in particular, has given us a very close-up inspection of Cameron and his body language. That he has created such a swift as well as positive impression is surely down to his open, televisual demeanour. TV sniffs these things out like a bloodhound.
Compare and contrast David Davis, the original frontrunner, now the make-weight. The confidence seems forced, the tone strident, the delivery less compelling.
And the message? Ah, who cares? There's plenty of time for boring things such as policies and visions and manifestos. What excites the Tories (and is giving Blair and Brown something to think about) is that they have found someone who won't come across as ever so slightly weird as, let's face it, the past four Conservative leaders have. Cameron is, in effect, Tory Blair.
It is no accident that the TV news has presented the Tory leadership contest as Big Brother evictions. Precisely the same human judgments are at work. And does that matter? I doubt it. We live in an age so saturated in media that it would be odd indeed if we chose political leaders who can't hack it under the studio lights.
I suppose, on balance, it might also be nice to think they had at least the occasional flicker of an idea about how to govern us ...