He used to hate sport. The closest he gets now is a gentle swim. But the Olympics...

The Interview - Ken Livingstone: The once-unathletic boy is now driving London's bid. Alan Hubbard hears the old political passion has found a refreshing outlet

With media murmurings gathering momentum and venerable IOC eyebrows still arched in surprise, the man chiefly responsible for placing American Barbara Cassani at the head of London's bid for the 2012 Olympic Games remains resolute that she is right for the job, and must be left alone to do it her way. "She'll either deliver or she won't," says London's mayor, Ken Livingstone. "Us interfering won't make it any easier. OK, so by throwing our weight behind her we may have made a disastrous mistake, but interfering now won't improve that. I actually think we've picked the person who can win us the Games."

Well, he would say that, wouldn't he, as it was he who pushed forcefully for Cassani when the two other stakeholders in the bid, the Government and the British Olympic Association, were both known to favour different candidates. But Livingstone is nothing if not persuasive.

Since Cassani, the 43-year-old former chief executive of Go Airlines, took over at the start of the month, there has been criticism that she seems a little girl lost in the combative world of sports politics, that she lacks the clout to impress the International Olympic Committee, and that she has got her priorities wrong. She did not show up in Paris at the World Athletics Championships until after influential IOC members had left town, and there is now concern that she seems to want to plunder the Friends Reunited website and surround herself with familiar faces from her former business world rather than tap into international sports expertise.

Livingstone is unfazed. "There were three other people who could have done it, but the advantage Barbara had was that she was a decade or more younger. She's hungrier than the others. I thought, 'This is the person who is going to fight the hardest for it'. For the others, it might have been the crowning part of their careers, but for Barbara it is going to be the biggest job of her life. If she gets this right she'll go on to one of the great world corporations." But will she be seen simply as Ken's Go-between? Livingstone insists that she is there to do London's bidding, not his. "You don't appoint someone at this level and then expect them to be your messenger. It was the same with Bob Kiley [another American who was a Livingstone appointee] at the Underground. We must all let her get on with it - me, the sports world and the Government."

At the moment, late-starting London lags some way behind its most serious rivals but on Tuesday, at the bid committee's new Docklands headquarters on the 50th floor of the Canary Wharf tower, Livingstone and Cassani will unveil major plans to set the ball rolling towards the vote in Singapore. Significantly, the presentation will be made to members of London's business community, whose financial support Livingstone enthusiastically courts.

There is little doubt that Livingstone no longer takes things quite as Red and, while no sports buff, he will be a major player in London's biggest-ever game.

Mayors are the fulcrum of all aspirant Olympic cities. Livingstone's opposite numbers in Paris and Madrid also chair their bids, and Montreal's Jean Drapeau was blamed for the infamous 30-year taxpayers' burden, known as "Drapeau's baby", following the 1976 Games." Livingstone promises much greater prudence, and even hopes that with a little luck he may still be in office to perform the mayoral ritual of handing over the ceremonial flag on the podium of the planned Olympic Stadium should London get the Games.

Yet this is a man who, on his own admission, knows absolutely nothing about sport. Now, with timing as sharp as a starting block's mechanism, he apparently has been converted on the road to Damascus - or rather, Stratford. "Ken is without doubt the best reactive politician in the country," says a former sports minister, Tony Banks. "He picks up other people's ideas, exploits them and runs with them."

But Livingstone argues that he recognises sport's value to the community, and especially now to his own electorate. Craig Reedie, the BOA chairman, recalls that when the idea of the bid was first put to Livingstone, he said: "Let me put my cards on the table. I'm not a sporty mayor. I really couldn't care less about sport. The nearest I've been to it was a snooker table at college. But I am absolutely clear that nothing will do for the city what a successful Olympics would. I will be its biggest fan."

Reedie adds: "He's been true to his word. He even came to Downing Street with us and shook hands with the Prime Minister, which seemed pretty good news politically. I think he's been terrific."

Livingstone' sporting aversion has lasted since childhood. "When I was a kid I was the smallest boy in a school of 2,100. I was the one who couldn't lift himself up the ropes in the gym. I was the kid who struggled in just ahead of the incredibly obese fat guy on all the runs. I was a sporting failure. It was just after World War Two, when most PE instructors in schools were rehabilitated Nazi war criminals. Their philosophy was if that you humiliate kids enough, they'll get better. I never did." He grew up in the Crystal Palace area, and vaguely recalls going to watch them once "when they inched into the First Division for a season", and hearing the sounds of the motor racing at the old arena "which seemed to drone on all Sunday afternoon". Now, at 58, his only concession to being a bit of a jock is swimming three times a week at a private health club near City Hall. Running is out, he says, because of arthritis, though he has started the London Marathon - started as in sending the runners on their way after "getting up at some godforsaken hour to fire the gun, looking down at Jimmy Savile trying to get to the front."

A lack of passion for sport is about the only thing he has in common with Lady Thatcher, though he does believe it should be encouraged in schools and as a vehicle for fighting obesity among the young.

So what will London get out of the Games? Quite a lot, he says, even if the bid fails (and realistically he believes there is a one-in-three chance of winning, with Paris and Madrid the main threats).

"Well, there'll definitely be an Olympic-sized swimming pool, and we can't allow Crystal Palace to go down at this stage. I know there's no guarantee it will be used in the Olympics, but London needs an athletics facility. I'm committed to saving the Palace, and I control the LDA (London Development Agency). Tessa Jowell's constituency borders it, and I know she's keen to keep it.

"We've just got to bang heads together, stop this silly dance between Sport England and Bromley Council over who is to get the blame, and put the money in. Other- wise we are going to look ridiculous again in the eyes of the sports world."

And as an experienced political hand, Livingstone realises that ridicule is one thing neither he nor London dare risk. But he believes there is a fighting chance of winning in a field which now has so many contenders he must have considered subjecting it to his own congestion charge.

"In a secret ballot, what they will look at is who can deliver a good Games. We will have strong case built on all the things the IOC are saying about regeneration, legacy and a green environment. I see this as a chance to make what must be the most polluted bit of Britain south of Middlesbrough a Barcelona on the Thames."

Livingstone also believes that his mayoral role could lessen the impact of the perceived antipathy towards London by Islamic nations because of the Iraq war. "Muslims love me. The Muslim community in London gives me solid support, and we're linked into a lot of international Islamic organisations. We'll make sure they are aware that London's mayor has a distinctive position from the Government on these issues. But I suspect that in two years the world will have moved on anyway."

To aid the London cause, Livingstone has put in a bid to stage a leg of the Tour de France in 2006 and, providing he is re-elected, he actually plans a rare visit to a sporting event next year. The Olympics in Athens. But he won't be watching the Games.

"I'll be sitting in the bar for five days at the hotel where the IOC members are situated. Me and my team will be there on a rota basis buying drinks, and we'll do the same in Singapore. My finance director will probably go up the wall, but I'm quite happy to drink for London." A good sport, then, if not a sporty mayor. So if his son Thomas, now eight months, eventually tells him he wants to be a professional sportsman, how would he react? "I'd say it was more rewarding than going into politics."

Biography: Ken Livingstone

Born: 17 June 1945 in Lambeth.

Education: attended Tulse Hill Comprehensive. Also spent eight years at Chester Beatty Cancer Research Institute (London).

Political career: Labour member of Lambeth Council 1971-78. Member of Camden Council 1978-82. Leader of the Greater London Council (GLC) 1981-86. From 1987-2000 served as Labour MP for Brent East. Member of the National Executive Committee 1987-89 and 1997-98. Elected Mayor of London as an Independent in May 2000.

Other: has written two books, If Voting Changed Anything They'd Abolish It (1987) and Livingstone's Labour (1989).