Ask the average politician how he’d feel about being left stranded, twenty feet above the ground on a broken zipwire, being filmed?

They’d probably not be jumping for joy –and with good reason, because the headlines would just write themselves, and not in a positive way. Osbourne? Economy going nowhere. Miliband (E)? Stuck, high and dry. Clegg? Let’s not even bother –he’s off to Europe soon enough.

It is the mark of how Boris Johnson has turned the basics of political communications on their head that his zipline moment burnished rather than diminished his popularity and his leadership credentials.

His achievements are, in many ways, bewildering. He is frequently incoherent. He uses Greek and Latin quips. He dresses like a bumpkin. He is overweight, and has hair last seen in a farmer’s field. He is, in short, the opposite of a modern politician. As one might quip, we know Mitt Romney, and he’s no Mitt Romney.

And that is the heart of it really. Politics is all about the moment, and perhaps the moment of the overly-groomed political campaign is over. Because that Romney comparison is telling –the Republican candidate-presumptive fails to elicit enthusiastic support, because he fails to exude authenticity. Indeed, the Romney Johnson put-down moment was a classic of its genre.

Cameron and Johnson both tried to ride the Olympics. That’s what politicians do. But Cameron failed because every time he was photographed watching the Games, or tweeted about them, there was the underlying suspicion he wasn’t really enjoying it. That he was doing the same as Brown, when he used to pretend to be wildly enthusiastic about the England football team. It all looks calculated, whether it is or not.

Johnson on the other hand, was patently enthusiastic about the whole thing. Amateur, occasionally a bit embarrassing, but enthusiastic and genuine nonetheless. At the beginning of Stone’s Nixon, the President’s henchmen, about to destroy his presidency by breaking into the Watergate Hotel, watch a film with the line ‘nothing sells like sincerity’. That’s the heart of Johnson’s comms plan, and his whole political persona. Be sincere. Be yourself. Be likeable. And that way, maybe being an Old Etonian Bullingdon man will work in your favour, in a way the PM can only dream of.

Will he ride this moment into Downing Street? Not on its own, no. But as a plan it’s sure beating the Prime Minister’s right now.

Francis Ingham is chief executive of the UK's PRCA.