Sir Steve Redgrave hailed London's 2012 Olympics victory as a tactical triumph for Prime Minister Tony Blair over French President Jacques Chirac.
Blair arrived in Singapore on Sunday to lobby International Olympic Committee members, while Chirac flew in to support Paris on the eve of the vote.
"To be able to take three days to come out here has made the difference.
"Chirac didn't have the chance to speak to members and was only here for the presentation," Redgrave told BBC Sport.
"The presentations were important, but it's that meeting and greeting and showing that full support right the way through. Hats off to the Prime Minister.
"Seb Coe has done an amazing job, but if you have to pin it down on one person it's Tony Blair coming out here and doing that.
"If you're the Prime Minister of a country, then you are going to get an audience with a number of people."
Paris had been considered the favourite to win hosting rights for 2012 from the start of the bidding process right up until just hours before the vote.
Blair, bid leader Lord Coe and right-hand man Keith Miller talk tactics
But London led the voting in three of the four rounds, with Madrid coming out on top in round two before dropping out in the next.
Blair decided to lobby IOC members despite having to fly straight back to the UK host the G8 summit of world leaders.
He was not able to take part in London's presentation before the vote, but he continued to meet members until the very last minute and addressed them in French in a recorded message on the day.
Chirac's strategy was to fly in late and focus on the presentation, where he addressed the members as "dear friends" and said he stood before them with a "great deal of emotion and passion".
The rivalry between London and Paris had been growing in intensity since Blair and Chirac clashed over European issues recently, and Chirac's arrival in Singapore came in the wake of a French newspaper story saying he had insulted British food.
Blair addressed the celebrating crowds in Trafalgar Square via a link-up from Scotland after the vote, and he telephoned bid leader Coe to congratulate him.
Redgrave, who with five rowing gold medals is Britain's most successful Olympian, led the athletes' group which helped draw up London's bid.
Blair presses the flesh with wife Cherie and footballer David Beckham (centre)
He was close to tears as he took in the magnitude of London's triumph.
And he said London's bid team had been irritated by claims from abroad that their campaign lacked support at the highest level.
"One of the things that annoyed me about the whole thing is that it had always come out abroad that the government wasn't behind our bid," he told this website.
"As soon as they came on board 18 months ago, they have been behind it 100%.
"There has been no doubt about it right the way through. Every message they have been giving has been so positive.
"But other countries were saying 'we've got much more government support than you have'. It just wasn't true.
"In some ways, them being negative about our public support has actually probably won us the Games."
But Redgrave said his heart went out to members of the Paris bid delegation as he did not believe a European city would get another chance to host the Games for some time.
"I spoke to a lot of the French guys in there, including two of the rowers. I'm welling up as I talk about it because I feel bitterly sorry for them," he said.
"In some ways it's a shame they haven't got it, but you know why I'm pleased they haven't."