A thunderous cheer went up at lunchtime today inside the smooth concrete ellipse in east London which, very soon, will acquire a final skin of glass and timber to become the 2012 Olympic velodrome.
But the volley of delight that issued from fluorescent-jacketed workmen and excited schoolchildren was not directed at the gold medal-winning cyclist and breakfast cereal salesman Sir Chris Hoy.
It surged instead towards the portly figure who had just trundled into the arena, run a hand through the haystack of his hair and clambered on to the Olympian's bike to execute two meandering circuits of the track.
As his turn around the velodrome proved, Boris Johnson could not be accused of failing to get into the spirit of things as he and Sebastian Coe kicked off the two-year countdown to the London games with a tour of the almost complete facilities of the Olympic village.
Sadly, however, the mayor is highly unlikely to be competing – a point cruelly and unnecessarily underlined by Lord Coe's mock-timing of his laps.
Hauling himself off Hoy's machine with the grace of a labrador dismounting a tightrope, Johnson admitted that the experience had not tempted him to upgrade the mayoral bike. Not least, he added, because the saddle was "bloody agony".
Hoy agreed that while the mayor is an experienced cyclist – "he rides to work each day" – he was probably not cut out for life as a racing demon.
"That would be a bit of a stretch," said the four-times Olympic gold medallist. "But he'll be there to watch."
Watching was the order of the day as Johnson and Coe, the chair of London 2012, led a gaggle of journalists, schoolchildren and volunteers across London to coo over the rapid progress of their sporting baby.
After the velodrome, the tour stopped off at the basketball arena – an enormous white tent reminiscent of a giant pile of raw meringue. As a pair of workmen patiently skimmed a corner of the arena's concrete floor, the former NBA centre John Amaechi shot hoops with a group of local youngsters and bemoaned Britain's attitude to the sport he loved.
"We lack the infrastructure," he said. "I came here on the Tube and I could have grabbed five kids off the Tube with the right physical attributes for the game."
Still, he mused, London 2012 would provide an excellent recruitment opportunity. He gestured around the interior of the meringue and its red-earth floor. "This place will be packed."
Across the river Lea – which, plans permitting, will boast a floating and double-sided giant TV screen to allow spectators to follow the action in the Olympic Park's landscaped gardens – lay the enormous melting surfboard roof of the aquatics centre, designed by the architect Zaha Hadid. And, over another bridge, rising from the landscape of cranes and mountains of earth in the constant drone of drills, diggers and cutters, lay the Games' centrepiece: the £537m main stadium.
Inside the palace of neatly-set concrete and fresh plastic seating, a race even more epic than the mayor versus the Bran Flake Man was about to begin.
Lolling around the blocks of a specially laid 100 metres track was another Johnson – Michael – and a handful of much younger sprinters drawn from the five host London boroughs.
After a lot of fidgeting and delays that the organisers of London 2012 would do well not to repeat, a cheer rose above the whine of helicopters and angle grinders, and the race began.
Beneath a humid grey sky, the retired runner – the winner of four Olympic gold medals and eight times a World Championships victor – was soundly thrashed by his young rivals.
Only a cynic would suggest that the 42-year-old threw the race in a fit of un-Olympian magnanimity to give his co‑competitors a taste of athletic glory.
If the gleeful shrieks of the young runners and the characteristic optimism of the mayor are indicators of things to come, then London will thrill and delight athletes and spectators alike in two years' time — not that organisers are taking anything for granted.
As he drowned out the bilingual PA system in St Pancras station in the morning, urging people to delay their trips under the Channel and listen instead to his Olympic tidings, Boris Johnson conceded that things were going "fantastically well".
So well, in fact, reflected the mayor, that "the smart thing for us to do would be to hold a snap Olympics and catch our sporting rivals out".
Coe shook his head in playful exasperation and his eyes performed laps around their sockets.