Tony Blair and David Beckham joined forces in Singapore as London made its final push for support ahead of Wednesday's decisive Olympics vote.
The prime minister declared a London Games would provide a sporting legacy for generations.
Mr Blair has been in Singapore to help final campaigning before flying back to Edinburgh to host the G8 summit.
London, Madrid, Paris, New York and Moscow all spent Tuesday promoting their bids to be the host city in 2012.
The decision from the International Olympic Committee on which city will host the 2012 Olympics is expected at 1246 BST on Wednesday.
That will come after the bid teams have made their final, official presentations to IOC members.
So Tuesday was effectively the last day for the cities to promote their campaigns, with all five calling on political and sporting heavyweights to champion their cause.
Aside from his photocall with Mr Blair, Beckham also joined a host of British ex-Olympians at a news briefing.
The line-up included Sir Steve Redgrave, Sir Matthew Pinsent, Jonathan Edwards, Colin Jackson and Denise Lewis and 11-time Paralympic gold medallist Dame Tanni Grey Thompson.
The London bid centres on plans for a new Olympic park in the East End, and Beckham - who was born in the area - said the Games would provide a huge boost.
"I've got friends that have got children that are growing up in the East End of London and they're already saying to me to have the Olympics in our manor would be a special thing for kids to have inspiration from different athletes from all round the world," he said.
Also in the British delegation in Singapore are England manager Sven-Goran Eriksson and footballing legend Sir Bobby Charlton.
Mr Blair said work would begin within 48 hours if London wins the right to host the 2012 Games.
"Everybody knows by my coming here the strength of the commitment. The day after, we're ready to start," he said.
Meanwhile, Mr Blair refused to be drawn into a row over French president Jacques Chirac's reported criticism of British food.
Mr Chirac - who arrived in Singapore on Tuesday to spearhead Paris' final push - is reported to have said the only thing Britain has done for European agriculture is "mad cow disease."
"After Finland, it is the country with the worst food."
Mr Chirac dismissed reporters' questions on the subject on his arrival in Singapore, saying: "We are in the Olympic world: that means fair play, that means that the best should win and that is what I want."
"And naturally I want the best to be Paris," he added.
Mr Blair, who is championing London's bid before returning to the UK to host the G8 summit in Scotland before the Olympic vote, also played down the issue.
"I don't disrespect the other cities that are bidding," said Mr Blair. "We should approach this in the right diplomatic spirit, which I will do."
"We have the determination to build something that doesn't just last for a few weeks but for a generation."
As the vote approaches after months of campaigning, British bookmakers have halved the odds for London, the second favourites behind front-runners Paris.
Paris' last-minute lobbying was stepped up with the arrival of Mr Chirac.
Several French sporting heroes, including NBA star Tony Parker and former Olympic champion athlete Marie-Jose Perec arrived on Monday to boost their bid.
"We are here to win," said Essar Gabriel, the deputy chief executive officer for the Paris bid. "More than ever, we are pulling out all the stops to do that."
New York has long been considered to be trailing Paris and London, but as Senator Hillary Clinton and boxing legend Muhammad Ali arrived in Singapore to lend their support to the bid, its leader Dan Doctoroff said victory was still possible.
"It's confusing and hard to predict," he said.
"It is a completely open race. We feel based on the feedback we've received from members of the IOC that we've got a chance."
Mrs Clinton told delegates: "Living in New York is like living in an Olympic Village - you have every language from every corner of the globe.
"We've lived the Olympics, now I'd like for us to have a chance to host the Olympics," she said.
Spanish Prime Minister Jose Luis Rodriguez Zapatero spoke on behalf of the Madrid bid at a 2012 briefing.
"Madrid deserves to win. It has the most support of its own population of all the cities," he said.
Also in Singapore to lend support to the Spanish capital's bid are Queen Sofia, Real Madrid star Raul, Tour de France legend Miguel Indurain and former tennis player Arantxa Sanchez Vicario.
At Moscow's only news conference in Singapore, Russia's bid team revealed that President Vladimir Putin - who has not flown out for the vote - will address IOC members in English in a taped message during its bid presentation on Wednesday.
Moscow mayor Yuri Luzhkov claimed to be happy with the evaluation report by IOC inspectors earlier in the year, despite reports that the Russian bid was perceived to be weak.
And the mayor accused western media of unfairly criticising Russia's bid in an attempt to further their home countries' causes.
Mr Blair, who with his wife Cherie, Culture Secretary Tessa Jowell and London bid leader Lord Coe, is now embarking on a last-ditch charm offensive on IOC delegates, promised to appoint a dedicated Olympics minister to oversee the Games.
Coe revealed that 30 of London's allowance of 100 delegates in the hall for the final presentation would be young people from east London, where the city would build its main Olympic venues.
Amber Charles, the 14-year-old basketball player from the borough of Newham who presented London's 2012 candidate file to the IOC in Lausanne last year, will be on stage with Coe.
IOC president Jacques Rogge has issued a veiled warning to cities to tone down the showbiz element.
"Yes, I like to see Olympic champions but I don't think he whole canditature process must be one of glitter and stars," said Rogge.
Rogge prevailed over the opening ceremony of the 117th IOC Session on Tuesday and emphasised that the commission's priority was to step up the fight against doping.
"In Turin, Beijing and Vancouver we shall intensify our efforts even more by increasing the number of (drug) tests," he said.