In bright sunshine, Brian Paddick's campaign bus drives slowly past Camden Town Tube station, with a dozen or so supporters on board waving and smiling. But Brian Paddick isn't on it. He is on the pavement, impatiently looking at his watch.
With nowhere to pull over, the old Routemaster, emblazoned with adverts for his one-hour-bus-ticket policy, trundles slowly up the street, almost unnoticed by the tourists, punks and office workers on their lunch break – a bright red metaphor for the campaign of the former top cop, reality TV star and Liberal Democrat candidate for London mayor, struggling to break into the Ken and Boris show.
That's not to say he lacks a sprinkling of the stardust enjoyed by his higher-profile opponents. Recognised once or twice by passers-by, the one-time jungle inhabitant on I'm a Celebrity, Get Me Out of Here! wears his celebrity lightly. Some have questioned his credibility. "There are not many politicians who can appear naked on television one week, and appear on the Today programme the next. That's what happened to me."
The 53-year-old has no regrets about going into the jungle, but wouldn't repeat it. "I'm a bit of a complex character," he adds, sounding a little like someone boasting 'I'm mad, me'. He adds: "Maybe some people think I'm a bit strait-laced, but strait-laced people don't tend to go on a reality show naked." Enough with the nakedness.
History is repeating itself. Mr Paddick was the Lib Dem candidate up against Ken Livingstone and Boris Johnson in 2008. This time, bus fiascos aside, he says the campaign is more professional, better staffed and better financed. "People are going to realise there's a viable alternative." Yet last time he polled just 9 per cent of votes. Strategists are hopeful of breaking into double figures in May's election.
The campaign-trail soundbites come easily – Lib Dems are "no longer the party that cannot win elections", "raising millions out of tax", "pupil premium", "pension rises". Criticism of his rivals follows. Mayor Johnson is more interested in "doing documentaries about his Turkish origins and writing columns for the Telegraph". While unimpressed with Johnson as a "caretaker" mayor, he is vitriolic about Livingstone. "He really is unpleasant."
Polls suggest a third of Labour voters won't back Ken Livingstone; he is "evading tax – OK, legally"; and gaffes have raised doubts about the Labour candidate's reputation as an opponent of discrimination. He suggested the Jewish community was too wealthy to vote Labour, and said the Tory party was "riddled" with homosexuality.
Mr Paddick says: "I remember a big black guy who used to teach us in the police about racism. He used to say that if it looks like a duck, and it quacks like a duck, it is a duck. And what Ken Livingstone is saying sounds like a homophobic anti-Semite. He may not be, but that's what he sounds like."
Lib Dem aides suggest Mr Livingstone cannot now win, and soft Labour support could yet switch to the Lib Dems. Brian Paddick is a different sort of candidate. No career politician, he spent 30 years in the police, rising to become Britain's most senior openly gay officer, later becoming the face of Scotland Yard in the wake of the 7 July London bombings. This marks him out from the other candidates, he says.
"Whether it was Ken Livingstone on the shooting of Jean Charles de Menezes or Boris Johnson over phone hacking, they are in awe of senior police officers. If a senior officer says, 'Don't worry, Mr Mayor, everything's OK', they just take it as read, they don't ask the right questions."
Three decades in the force saw massive cultural change. "The overt, blatant homophobia as well as the blatant sex discrimination and racism disappeared, but it was always there, bubbling below the surface, and it became more subtle." White male managers would make decisions in pubs and wine bars around Scotland Yard, excluding officers from ethnic minorities, or, like Mr Paddick, who were openly gay. "Senior officers wouldn't socialise with me, presumably because they thought it would be catching, or would damage their own reputation."
He has been a high-profile critic of the Met's handling of the phone hacking scandal, having been a hacking victim himself. He claims, with a hint of immodesty, that he has a "reputation in the Met for being a man of integrity" and has been contacted by several people who want to speak out about the culture of cover-up in the police.
"When I was at training school in 1976 they gave a specific example of a local restaurant owner who was giving free kebabs to local officers. When that guy was arrested for drink driving, he produced a notebook with about 300 police officers' numbers and said: 'These are the officers I have given free kebabs to, what are you going to do about my drink-drive charge?'."
I laugh, he doesn't. And that's the problem. His anecdotes are polished and delivered with aplomb; he lacks neither experience nor conviction. Yet his campaign remains a little dry – somehow unconvincing, passionless. He's on the bus, without doubt. It's just not certain where he's going to end up.