By Sarah Bell
BBC News, The Mall
The 2012 Olympics has a £9.3bn budget
They had been asked to party like it was 2012 - and the crowd at the Olympic handover party on The Mall duly obliged.
An estimated 40,000 people celebrated Team GB's astonishing success in Beijing, but were also anticipating the country's starring role in four years' time.
In the shadow of Buckingham Palace and overlooked by a host of London landmarks, there was excitement that it was now the capital's turn in the spotlight.
Jane Harman, from Lincolnshire, summed up the feelings of many in the crowd.
"I'm very proud we've done as well as we have. I had to be here today, it's such a momentous occasion," she said.
The closing ceremony from Beijing was broadcast on giant screens, and the eight-minute section hosted by Britain greeted by cheers.
Mayor of London Boris Johnson's appearance was met with chuckles and shouts of "come on Boris," then cheers when he successfully waved the Olympic flag.
London was now, officially, the Olympic host city.
Rob Lester, from Nottingham, explained why the event has more than just a sporting significance.
"When it comes to the Olympics, they're just brilliant, they bring out the best in everyone, they're just such a happy event," he said.
He added that while Britain may not be able to compete with the Beijing spectacle financially, London could still do a good job.
"It means a lot that London has them. It's something to be proud of, instead of just moaning about the country it's time to strike out and show what we can do.
"We're not going to be able to compete with all the amazing graphics Beijing has done, but in our own way it will be equally good."
Many people said they hoped sport in Britain would be the main beneficiary of 2012, especially after the success in Beijing.
Ryan Holloway, 28, said: "If we can maintain that funding and get more investment, that would be great."
Call for support
Alex Taylor, 28, from Eastbourne, said the British had a tendency to talk the country down, and that needed to change.
"The more people start thinking positively and start promoting the London Olympics as a positive thing, the more successful they're going to be.
"They're going to be good for business, good for development and infrastructure. In the long-term there will be all the facilities which we wouldn't have if we didn't have the Olympics."
The crowd waved a sea of flags
Neil Flynn, 46, from Feltham in west London, said the capital had to do a good job in 2012.
"It's a once in a lifetime thing. For it to be in my country, I'm so very proud", he said
"We should be positive. We've waited for years for it to come back, people just need to get behind it and support their country."
But some did question whether the capital could cope.
Charlotte Black, 25 said: "The Tube is already so crowded, I can't imagine it then, with all the tourists coming over, it will be a nightmare."
The party really kicked off when the cast of Queen musical We Will Rock You got the crowd singing and clapping along to its title track, followed by We Are The Champions.
Definite crowd pleasers, the songs maybe also carried a promise of what is in store in 2012.