Firework smoke and a sense of optimism at London 2012

Day one, London 2012. It's 1am and the air is still thick with firework smoke and optimism as I join the crowds leaving the Opening Ceremony. Even the French seem persuaded by Boyle's eccentric and modestly patriotic show. Raphael Laidz, 26, a banker from Calais, has a massive grin on his face. "I was sad France didn't get the Games since it's my country, but I think tonight we have to be happy, as the best bid won," he says.

By 1.30am I've made it on to the packed Underground. But this is no commuter crowd; everyone is smiling and talking animatedly. A tired and emotional Australian exchanges superlatives with an earnest businessman from India – tonight, they say, London is "magnificent", "beautiful" and "the best place to be in the world".

At 3am, I arrive home still buzzing and after a couple of hours' sleep it's time to go again. At 7am I get on a half-empty bus cutting quickly through London, with none of the fabled travel chaos.

Walking down Regent Street at 8.15, beneath hundreds of enormous international flags, the excitement starts to build again. The streets are relatively quiet still, but there's an electric sense of anticipation – most people seem to be either on their way to Olympic events or guiding others to them.

I arrive at Horse Guards Parade at 8.30, with the crowds queuing to get into the beach volleyball. Colin Fisher, 22, from Edinburgh, is waiting with two friends dressed in Top Gun jumpsuits, sipping from cans of M&S lager. "We're here for the, er, Olympic spirit," they giggle, as they extol the feminine virtues of various teams.

At Green Park by 8.45, I find thousands gathering to cheer on Mark Cavendish, Bradley Wiggins and the rest of Team GB for their start in the road race. Designer Doug Poulton, 41, and curator Jane Dunn, 38, have cycled from East London to see their heroes. "It's so special to be able to watch him here in London," says Poulton.

At 9.45, royalty arrives. Charles and Camilla chat to the British cyclists lined up at the start line. With under three minutes to go until his race starts, Wiggins shows his class by chatting with one of the volunteers who's come to wish him luck.

And they're off! At 10, a riot of colourful bikes and helmets swish past in fast-forward and the crowd screams and whoops its approval.

Next, up to St John's Wood on the Underground at 10.45 to see the archery. I arrive at 11.30, in the wake of Team GB's disappointing exit at the hands of Ukraine. The volunteers are despondent: "Don't suppose anyone will write much about the archery."

Back on the Underground again. Never before have I run so far, on so little sleep.

Cutting through Green Park to Buckingham Palace at 12.25, I find visitors from around the world having their photographs taken and waiting patiently for the return of Wiggo et al. Betty Rogers, 49, and her niece Becky, 21, are over from Chicago. "I've taken all of my nieces and nephews to the Olympics since Atlanta in 1996 and now it's Becky's turn", she says.

Back at the Mall at 3.30, there are roars of disbelief in the press room as Britain slips behind. When the cyclists finally come into view they are led not by the familiar jerseys of Team GB, but by a man in the blue and yellow of Kazakhstan.

Just after 4pm, when the names on the podium are confirmed, an eerie silence falls over the Mall. But, by the time Alexandr Vinokurov has stood teary-eyed through the Kazakh national anthem, they are ready to cheer again.