"Forget about your troubles and dance," said Macy Gray.

And they did - 6,000 tickets to the New York City concert were given out to the firefighters, police officers, other rescue workers and the families of those who lost their lives at the World Trade Center.

For six hours, they remembered those who died on 11 September and they also remembered how to enjoy themselves.

Pop legend David Bowie kicked off the concert with a tribute to local firefighters.

"My fellow New Yorkers, I sincerely would like to say hello to my local ladder company - you know who you are. It is an absolute privilege to play for you tonight," he told the audience, followed by a rendition of his hit song Heroes.

The line-up also included Billy Joel, Destiny's Child, James Taylor and Jon Bon Jovi, while other bands, including Irish rock group U2, sent recorded messages of support.

Billy Joel got an especially rapturous response when he sang "New York State of Mind".

Sir Paul McCartney, who organised the event in less than five weeks, debuted a song called Freedom which he had written following the attacks.

"This is one of the greatest nights for me," he told the crowd.

"I want to thank you guys for everything you've done, on behalf of the British, on behalf of America, on behalf of the world."

Middle-aged firemen and police officers and their wives danced to Mick Jagger, Eric Clapton and The Who, while Backstreet Boys and 'N Sync kept their children happy.

As well as a host of famous performers on stage, celebrities in the audience included Hollywood stars Harrison Ford, Jim Carrey, Meg Ryan, Richard Gere, John Cusack, Mike Myers and Gwyneth Paltrow.

The concert at Madison Square Garden, which raised at least £9m ($14m), helped boost the morale of individual families, the forces devastated by the suicide attacks and New York City as a whole.

Many families turned up holding photographs of their deceased relatives and one group wore T-shirts with the slogan "Dad, we will never forget".

Therapy

"It's a happy thing to do, other than stay at home and be depressed," said Ryan Farrelly, whose father was one of the 343 firefighters who died at the World Trade Center.

Jeff Borkowski from the Hazardous Materials 1 station of the Fire Department of New York lost 19 colleagues in the suicide attacks.

He told BBC News Online that going to such a high-profile concert with his colleagues, family and the families of those who perished would be a form of group therapy.

"It will be extremely emotional. I've been going to funerals non-stop for five weeks now and there's not much emotional energy left," he said.

Ryan Hannafin's uncle was another of the firemen who died on 11 September.

He thought the concert would provide some welcome relief, especially for those firefighters who have been working continuously at Ground Zero and elsewhere around the city.

Most of the firefighters were dressed in their ceremonial uniform while others wore jeans and FDNY T-shirts.

In today's New York, they mingled freely with the city's elite in black designer jackets and evening dresses.

By the end of the show, firefighters and police officers were singing on stage with Sir Paul and John Bon Jovi.

Security was tight for everyone.

As a procession of black stretch limousines with tinted windows arrived, bringing heavyweight politicians and showbiz stars, sniffer-dogs from the bomb squad ensured they were not carrying explosives.

Tickets for a concert featuring such an array of celebrities cost between $250 and $2,000.

But it was a sell-out.

One man who had paid $1,000 for two tickets said: "It's a great cause and a great musical line-up, so it's worth it. I already made a donation, this is what we can do to help."

While the New York City concert provided some light relief for thousands of families who have had such a harrowing six weeks, the mood was still far from normal.

Jokes about being too afraid to open envelopes were too close to reality for most of the audience and raised few laughs.

Insulting the Taleban and Osama Bin Laden went down much better, as did songs praising New York's resilient spirit and Mayor Rudolph Giuliani, who received a standing ovation when he appeared on stage.

Some of the firefighters and police officers will be nursing sore heads on Sunday morning.

But for the first time in five weeks, it will be a result of enjoying a good Saturday night out, rather than from grieving for dead friends and colleagues or inhaling the smoke and dust at Ground Zero.