They had an hour to fill before the music began and they chose to plug the gap with a near hysterical exercise in pre-emptive nostalgia - already looking ahead to the day when we'd look back on all this.
Fearne Cotton, who is to incisive interviewing what Burkina Faso is to aerospace industries, did a lot of the heavy lifting. "Do you think it's going to be an amazing event like Live Aid?", she asked one concert-goer - who correctly guessed that saying "no" wasn't an option. Jonathan Ross was at it too, suppressing his natural instinct for impertinence. And the celebrities who had turned up early knew where their duty lay as well: it was, Chris Martin of Coldplay announced, "the greatest thing that's ever been organised". Never mind D-Day or the moon landings - mere logistical picnics by comparison - this was the biggie.
The hyperbole and self-congratulation was a bit hard to take. As act after act declared that it was the least they could do, you couldn't help but think that it probably was. And the crowd's commitment to global justice might have seemed more selfless if they hadn't been drawn to Hyde Park by the concert of the century. But then something began to build. Paul McCartney and U2 stood the hairs up on the back of the neck - with Sergeant Pepper and the first of many pointed lyrical rewrites. "Take these sunken eyes and learn to see" sang Bono, twisting the words of "Blackbird" to the day's theme. "Who are you?" asked The Who, as mugshots of the G8 leaders flickered behind them. Others didn't bother: Pink Floyd, warily reunited after 24 years, sang "Don't give me that do goody-good bullshit" and in Philadelphia Bon Jovi insisted that "We've got to hold on to what we've got".
Back in London that hot stadium favourite Kofi Annan was more on message. "This is the United Nations", said the secretary general -- though frankly it didn't much look like it. Until Youssou N'Dour appeared with Dido (in one of the more moving duets) there wasn't an African face to be seen - and the BBC's occasional cutaways to the Eden Project concert made it obvious that the stars of that continent had been relegated. The truth though, was that this wasn't about them. The line that appeared again and again above the stage - "Eight men in one room could change the world" - was from Richard Curtis's television film The Girl In The Café and it confirmed what was happening - that political events were being reshaped as a popular drama with billions of extras.
Without Live8, next week's summit would have been an irrelevance for most people. Geldof, Curtis and the rest have turned it into a cliffhanger. It will be a great deal harder for those eight men to deliver the usual compromised unhappy ending.