By Anna Browning BBC News, Trafalgar Square

Cycling was among the activities on offer at the anniversary party

It is a year since London won its bid to host the 2012 Olympics, a day perhaps most memorable as the high before the horror of the 7 July bomb attacks.

But for those behind 2012, that was no reason not to mark London's success 12 months ago.

Trafalgar Square - the centre of the 2005 celebrations - was again the scene of a party on Thursday.

There was song, there was dance, there were dignitaries - Prime Minister Tony Blair included - but mostly there was sport.

While red buses, black taxis and other weekday traffic ground their way around Trafalgar Square, hundreds of schoolchildren had the chance to try their hand at fencing, cycling, basketball, rowing and sprinting - with Nelson's Column towering overhead.

And for Olympian Sebastian Coe, chairman of the London 2012 organising committee, who was in Singapore for the announcement, it was an opportunity "to get to feel for a little bit of what happened last year".

The party also kicked off a series of summer celebrations, which will see 150 sports events take place in London.

It makes me excited about 2012 Pearl Nakitto

And a double-decker roadshow bus set off on a 3,000 mile journey around the country - aiming to get the rest of the UK onboard.

"Be part of it, 2012" was their slogan, while the emphasis was to inspire young people to get involved in sport - not just watch it.

Pearl Nakitto, 13, from Whitton Sports College, Twickenham, is an athlete - and aiming to compete in 2012, she said.

In Trafalgar Square, though, she had left sprinting behind to try her hand at fencing.

"Being here, it makes me excited about 2012," she said.

On the moment when London won its bid, she said: "I wasn't here, I was at school, in science - but it felt great."

James Lee, 14, from Hounslow, London, remembered feeling "really happy".

"I love sport and I really want to go to the 2012 Olympics," he said. "It's going to be awesome."

It's good to celebrate, to bring everyone together Jonathan Edwards

For Jonathan Edwards, triple jump world record holder and member of the 2012 Olympics' organising committee, there was no better time to celebrate their success - despite the obvious shadow cast by the anniversary of the bomb attacks.

When London won the bid he was with its delegation in Singapore.

Did he think it out of place to party during a week of July 7 commemorations? No, he said.

"We didn't get the chance to celebrate last year," he said. "It's good to celebrate, to bring everyone together."

And besides, sport bridged divisions.

According to Sebastian Coe, the Olympics would give London an unparalleled opportunity.

"This will be the opportunity to show this city and this country in a way we have never had the opportunity to do before.

"This will be a challenge, but we have an exciting road ahead."

Two days 'intertwined'

While one year had passed, there were another six years (2213 days to be exact) until the opening ceremony, Culture Secretary Tessa Jowell told the crowds.

She pointed out that we all remember where we were the moment the president of the Olympic committee opened the envelope - and where we were a few hours later when the attacks on London happened and 52 people were killed.

"Forever these two days will be intertwined in people's memories," she said.

But they both demonstrated the strengths of "our city".

It showed its resilience, its optimism and fortitude.