Watching Boris Johnson in mayoral action, it is hard to resist the impression of a man playing a part with increasing daring and conviction.

Successive photo-opportunities outside City Hall this week – to promote London’s part in the England 2018 World Cup bid, and British basketball’s part in next month’s four-nations tournament at the O2 Arena  – were energised by the presence of this tow-haired, strangely bulky figure who still seems unwilling to commit to the dull business of being a serious politician.
 
As the former Classics scholar of Balliol College, Oxford settles himself in the midst of a group of children from Arsenal and Tottenham’s community projects, all in team kit and bearing scarves with the logo: ‘Back the Bid’, he is gamely interacting. “How are you?” he asks a startled Tottenham Hotspur girl. “Hello. How are you doing?” he inquires of an equally mute Arsenal follower. “God, it’s hot, isn’t it?” he asks of no one in particular, an assertion that receives no particular response.
 
Having displayed the roving eye and the challenging rhetoric of a stand-up comedian, he is now off on a riff for the assembled audience of focusing photographers, impatient reporters and tense PR girls. “We’ve got the climate. We’ve got the facilities. We’ve got everything the world could possibly want,” he maintains, while eschewing the offer of a scarf. “I’m not having that round my neck.”
 
Then comes a brief exposition on the nature of time - “2018. Long time away, isn’t it?” – before he strides away to his next gathering. “I was told I had to wear a tie,” he says to me as he passes, his hand straying to his neck.
 
This exercise is a relatively small ask for the man who just 10 months earlier stood at the epicentre of the Beijing Games to receive the Olympic flag on behalf of the city entrusted with the next gathering of sporting nations – a task he performed with the bemused air of a boy longing to put his hands in his pockets.
 
Leaving Tottenham and Arsenal behind, the Mayor of London makes his way down into the amphitheatre that has been constructed next to the leaning tower of London in which he conducts his day-to-day business. Very soon he is standing amongst unnaturally tall men, holding a customised basketball shirt bearing the logo “Mayor 1” which, in his own rather startling description, is “gently cut away to reveal substantial quantities of armpit.”
 
That Boris – he just can’t leave it alone. I find myself thinking of an interview I undertook with the newly installed Sports Minister, Tony Banks, soon after New Labour had swept exhilaratingly to power. Banks had just turned down an invitation to watch the FA Cup final, involving his beloved Chelsea, from the Royal Box.
 
As an aide twitched fatalistically at his side, Banks teetered on the brink of decorum – and then plunged headlong over it.
 
"The idea of throwing my arms around the Queen when Chelsea score, or screaming ‘the referee’s a wanker’, which I’m likely to do, probably would not go down too well in the Royal Box,’ he reflected. “I’m not going to have my enjoyment of one of the great days of my club spoiled by being next to Royalty of no fixed abode.”
 
As his assistant quietly turned over ideas of a fresh career in his mind, the late lamented MP for Newham North West offered a quiet smile of satisfaction…
 
But now the press have moved in, and the Mayor is being duly pressed on his assertion that the Olympic Park will benefit Londoners before, and more importantly after, the Games had taken place. “How?” he responds to the earnest question of a female reporter. “With energy, dynamism and the commitment of you and yours.” He’s Bill Murray, twinkling. No one’s twigged him yet, and the private joke is just getting funnier and funnier. But here’s the twist – like a cinema audience, we are all in on it. And we’re loving it.
 
As Johnson speaks, he is standing in the middle of an immeasurably potent advertisement for the capital he represents. Across the river, the original Tower of London warms its ancient stones in sunshine blazing from a cloudless sky. Union and St George flags on the span of Tower Bridge ripple in a merciful river breeze, Thames clippers cleaving the green beneath. In the stepped gardens on the south bank, short-skirted and shirt-sleeved citizens bask like figures in a Seurat.
 
Where else, you think, where else would any major sporting event want to be? And where else would you find politicians able to promote the sporting aspirations of the nation and the capital with such glorious eccentricity?
 
Johnson and Banks could hardly be described as fellow travellers in a political sense. But in terms of their essential spirit, that description holds good.
 
Mike Rowbottom, one of Britain's most talented sportswriters, has covered the last five Summer and four Winter Olympics for The Independent. Previously he has worked for the Daily Mail, The Times, The Observer, the Sunday Correspondent and The Guardian. He is now freelancing and writes regularly for insidethegames