You think only journalists were embarrassed by their premature predictions of Hillary Clinton’s political death? David Cameron, seduced by comparisons of a wooden Gordon Brown to a robot-like Hillary, may also be regretting talking up his own resemblance to fresh-faced Barack Obama. “I’m enjoying watching him. I think we need the same sense of possibility here,” the Conservative leader said, also praising his message of “change you can believe in”. How the prime minister must have guffawed as the results of the New Hampshire primary came in.

The race for the White House allows us all to wallow in personality politics. So much more entertaining than the “ishoos” that Tony Benn always protested were paramount. The London mayoral elections in May are the closest thing we have to American-style pure democracy. An electorate of more than 5m, the biggest single election for an individual in Britain and the third largest in Europe after the presidents of France and Portugal, will decide the fate of the capital. Ballyhoo, blarney and barnstorming lie ahead.

For all that, it is also a test of party fortunes. “It would be a great boost for Tory fortunes if we win; a victory would create a further sense of our inevitability,” says one top Tory strategist. Then hurriedly he takes out insurance against defeat by claiming that “London is really a Labour city”. The two parties are already at level pegging in polling. Brown knows the dangers. He is said to have grumbled: “We’ve lost Edinburgh and we can’t afford to lose London.”

Three candidates not seen as party stooges will battle it out in a lively contest. The theory is the London public rewards those who say what they think, often quite rudely. The spoils go to the person who, in the words of Senator Clinton, “finds their own voice”.

In the right corner I give you that bumbling Tory toff, that Wodehousian wonder, the one and only Boris Johnson. In the left, mayor Ken Livingstone, twice elected Labour incumbent, cheeky, chirpy man of the people, newt fancier, “Red” or “Citizen” Ken. The man in the middle is Liberal Democrat Brian Paddick, a gay former policeman who pursued a tolerant policy towards cannabis in Brixton. Mavericks to a man, they are all interesting figures (interesting as in the Chinese curse of “May you live in interesting times”).

Though the powers of the capital’s mayor in centralised Britain are still dwarfed by those of New York’s, they are growing. The orphan child of Tony Blair’s one night stand with real local democracy, the London mayoralty commands a budget in excess of £10 billion and has wide responsibility for transport, police, housing, planning and the environment.

Livingstone is a formidable opponent. He knows the drill; he defied Labour’s leadership to run as a successful independent in 2000. Seven years later, now back in the Labour fold, Red Ken is as happy courting corporate finance for new skyscrapers as he is consorting with dodgy Muslim clerics. He can boast of his role in getting the Olympics for London (though Blair might contest that) and introducing a revolutionary congestion charge and a sensible transport ticketing service.

In New York “Hizzoner” the mayor often wears his party label as a flag of convenience for personal ambition: he even has his own eccentric take on foreign policy. So too with Ken, who makes bizarre private deals with Hugo Chavez, the Yankee-hating leader of Venezuela, to give Londoners free heating oil. “Everyone likes Ken Livingstone except the people who know him,” was the memorable verdict of Neil Kinnock, the former Labour leader.

Similarly Boris is perhaps the only other politician in Britain better known by his first name. All those this talented writer and self-publicist has let down seem to forgive his sins - even the Anfield football crowd were chanting “There’s only one Boris Johnson” within weeks of his grovelling to the citizens of Liverpool for alleging they wallowed in “victim status”.

Surprisingly he is not his own worst enemy – Fleet Street rivals, many of them Tory, compete for that honour. “Almost as soon as he is out of short trousers Boris is seen as indulging in sloth, deceit, manipulativeness, selfishness, irresponsibility, concupiscence and, eventually, adultery,” wrote Simon Heffer, his Telegraph colleague. Yet Boris is the Russell Brand of contemporary politics; behind the comedy is a ruthless eye for the main chance.

Johnson is an unlikely representative of modernising Toryism. He may be an Old Etonian and a cyclist but he shares none of his leader’s deference to political correctness. Typically, in his last Daily Telegraph column, he defended Nicholas “Fatty” Soames, his fellow MP, who faces criminal proceedings after being photographed with a child on the back of a quad bike on an open road. “A grotesque waste of police resources,” he wrote, adding gamely: “What else can I say to offend the mayor’s spin doctors?”

Rod Liddle, my colleague, sorrowfully admits to being responsible for the left’s damaging charge against Boris – that he is racist. Liddle let slip to an interviewer the story that, bored beyond measure by some po-faced Unicef officials in a truck on the Kenyan-Uganda border, Johnson had called out: “Come on, let’s get out and see some piccaninnies.” A tasteless quip, followed by his dispatch of four prostitutes to Liddle’s room at 4am bearing the message: “Your friend said you needed us.” Jolly japes indeed.

Still, Livingstone’s intemperate outburst to a Jewish reporter for the London Evening Standard, likening him to a Nazi concentration camp guard, takes some beating too. He also called the American ambassador “a chiselling little crook” for refusing to pay the congestion charge.

I would hate Paddick to feel left out. Given a choice between death and his former divisional commander’s company, Sir Ian Blair, the Metropolitan police commissioner, would rather take the poison.

Last week Ken, Boris and Brian battled it out in a debate televised on ITV in front of a live audience of party loyalists, with two people watching at home (I was one of them). Boris’s supporters seemed disproportionately Asian and black, while Ken’s had more than a fair sprinkling of the white London working class (a group suspicious that he favours immigrants). Paddick’s team were typical Liberal Democrats, poor fellow. Chairing this kindergarten, appropriately, was Konnie Huq, ex Blue Peter presenter.

All sides claimed victory. I thought Livingstone did well on gravitas, though Johnson’s verbal footwork was fleeter and Paddick was brave on his first real political outing.

Steve Norris, a two-time Tory loser to Ken, thinks Johnson’s chances this time are good. “When I lost the first time, the Tories were 21 points behind Labour in the national opinion polls. The next time the Tories were only 11 points behind and I got much closer.” Today the Sunday Times poll gives the Tories a 10-point lead over Labour. On Norris’s logic Boris is a long way home, if not exactly dry.

“Boris’s real issue is to talk about crime and the fear of crime. People don’t like the Met, don’t think they are efficient and dislike the rudeness of officers they meet,” Norris adds. Phew. Even Boris wouldn’t put it that baldly – but he is pointing to the 27 children murdered in London last year and highlighting housing shortages.

Cameron gave me a pleading smile, as if he desperately wanted me to think Boris was a good idea as his candidate when it was first announced. “Boris is a very serious politician,” says another Cameroon primly.

If Boris wins, his Tory critics outside the Cameroon camp predict trouble. That was Labour’s original worry about Livingstone. In the 1980s, when he was leader of the Greater London council, Ken’s loony-left antics undermined the national party. As mayor, Ken proved the doomsayers wrong. Mayor Boris is more likely be accused of laziness but won’t be an ideological liability.

But if Boris loses and loses badly, it will be Project Cameron’s first electoral setback. That does matter. Then the puritans will fault the Tory leader’s judgment for picking him, though no other titans were available. With Boris about only one thing is certain – the custard pies start flying. Yikes!

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