By David Sillito
BBC News Arts correspondent at Hyde Park
Even Sir Elton John looked a bit startled.
Sir Elton played a duet with Pete Doherty of Babyshambles
There is a little group of green huts in a park in London, outside them the United Nations Secretary General Kofi Annan was having a quick chat with Chris Martin, the lead singer of Coldplay.
Sir Elton, Richard Ashcroft, Keane and Annie Lennox all passed the time watching this bizarre little backstage crowd.
A few minutes later Microsoft's Bill Gates wandered through on to the stage to introduce Dido.
Backstage at Live 8 feels like being at a friend's barbecue, if your friend happened to live in a portable home in Hyde Park and is fabulously well connected.
There is no shouting or panic, no sense of rock and roll chaos at all, but there are some lovely char-grilled burgers and glasses of Pimms.
The comedy writer Richard Curtis is wandering around with a bit of a furrowed brow, but then that might be his normal look off screen.
Perhaps it is the presence of Bob Geldof and Kofi Annan that has given the place a sense of seriousness.
Sir Elton said he felt "a little nervous" but was word perfect with the message of 'Make Poverty History'.
Midge Ure, who is responsible for the Live 8 event in Edinburgh on Wednesday, was more than fluent about the agenda facing the G8.
Singer Youssou N'Dour said he was glad there was a stage in which a hopeful vision of Africa could be presented.
Talking to the fans, most remembered to say they were here for "the cause" as much as the music.
Fans had been gathering in Hyde Park since early morning
Interestingly, of the less than scientific sample I took, it was bands such as The Killers, Razorlight and the Scissor Sisters that people were talking about.
The only name from the "aristocracy" of rock and roll that was mentioned was Pink Floyd.
Given that they are reforming just for this event perhaps explains that, but most people said they simply wanted to be here.
But perhaps the most telling thing that Sir Elton said was that in 1985 "people doubted they could pull a thing like this off", but now - 20 years on - huge festivals are commonplace.
'Another day's work
Sir Elton himself was about to fly off to Dublin and Philadelphia to perform.
And this is not unusual. This is the ultimate example of how industrial the top end of pop music has become.
There are 5,000 people involved in making this event happen and amidst all the talk of this being "the World's biggest cultural event" the stars look as though it's just another day's work.
But one man who looked as though he was truly moved was Pink Floyd's drummer, Nick Mason.
The band is famous for its long-running disputes and the line-up that created its most successful records has not played together since the early 1980s.
They are now back on stage at Live 8. Mason said they were doing it for political reasons.
"The idea is to make people think about the issues," he said.
"If you look at a rather elderly band getting back together after years of squabbling then it's likely to make you think."