Nigel Farage's smile makes him the most effective communicator of the party leaders in the 2015 general election campaign.
Given how much they rely on words, it's no coincidence he's the only senior politician whose best asset is their mouth.
There is nothing like a decent smile for attracting votes. Just look at the greatest smile in global politics, Barack Obama's. Or the landslide wins of Tony Blair's brilliant grin.
Like theirs, Farage's smile tells the voter: "I'm happy to be here, I'm happy to talk to you, I'm having a good time and I'm likable."
Party leaders lacking this basic weapon in their political armoury are losing out. David Cameron's permanent state of tension makes him so uptight he is physically restrained from smiling well or often enough. Sometimes when Ed Miliband smiles it's hard not to wonder: 'what did you have to do to summon that up?'
But for Farage the smile comes easily. It's an important part of his winning attitude - a very obvious enjoyment of the rough and tumble of British politics.
Perfecting the art of looking like you're having a good time is the secret to the Ukip leader's success. Everyone likes the guy who's enjoying himself. And if he's saying authoritative things at the same time, he's likely to win over more than he loses.
The energy is infectious. Farage is very comfortable with people - typical of extroverts - and there's an authenticity about him that appeals greatly. His confidence is something disillusioned voters on the right have warmed to and really enjoy.
That smile isn't just about fun, either. Farage is viewed as ballsy rather than an equivocator. That fits with Ukip's outsider approach. It is the upstart party that can say what it thinks.
It's harder for Cameron and Miliband. They face the difficult balancing act of persuading the country that their policies are in their best interest as well as being genuine and approachable. That's not easy in this 21st century pressure cooker environment. When voters detect a lack of authenticity, they hate it and their discontent is clear.
Farage, by contrast, can shoot from the hip, which helps him to be perceived as authentic. He offers an antidote to the controlled stage-managed soundbites that so often emanate from the Westminster village. He is unfettered. He doesn't seem to be controlled.
The Ukip phenomenon's success is also about combining his obvious enthusiasm for the fight with being decisive. None of the other party leaders pull off this double-act quite as well.
When he is being decisive he doesn't chop, like Cameron - he just makes a point, like anyone would when talking about a subject down the pub. It's a striking change from the norm which has struck a chord with those that feel politicians are cloth-eared and patronising.
His secret is the whole 'down the pub' persona. Farage's 'I like a pint and a fag' brand is better than anything else on offer - and certainly more fun. Nothing celebrates 'I'll do what I like' than smoking a cigarette.
It's a faux libertarianism that works well for Ukip and invites parallels with the Tea Party in the US. Ordinary voters won't spot that, of course. What they'll recognise and value is an authentic personal brand.
This matters because when you ask people why they're backing the person they're going to vote for, the answer is often 'because they speak my language' - not because they're going to implement policy X or reform Y.
His downfall, however, will likely be the rest of his party - who at the best of times are off-message and lack the finesse to charm the rest of us.
With Farage's smile dominating the airwaves this spring, though, Ukip needn't worry. His is a one-man revolution. No wonder he's enjoying himself.
Nick Smallman is chief executive of communications training firm Working Voices