Live Aid, the legendary 1985 charity concert featuring stars from Paul McCartney and Queen to U2 and Madonna, is being released on DVD for the first time.
By Ian Youngs
BBC News Online entertainment staff
It was one of the defining events of the 1980s, with an unequalled musical line-up contributing to one of the most memorable TV broadcasts ever made.
The Live Aid concert was split between London and Philadelphia
But Live Aid's transatlantic 16-hour show was almost not recorded at all.
When organiser Bob Geldof was persuading artists to take part, he promised it would be a one-off, never to be seen again.
That way, he said, they did not have to worry about contracts or embarrassment if they messed up amid the chaos of the day.
If Geldof's plan had been followed, Live Aid would have remained a fond but fading memory.
But BBC Radio 1 concert co-ordinator Jeff Griffin realised history was about to be made - so recorded it anyway.
Mr Griffin confronted Geldof at a meeting a month before the event. "I collared him for about 30 seconds afterwards and just looked him in the face," Mr Griffin tells BBC News Online.
"I said 'Bob I hear what you're saying, but I have to disagree with you - I just think it would be irresponsible not to record it because this has all the makings of something very, very special'."
Prince Charles and Princess Diana were among 72,000 at Wembley
Geldof secretly acknowledged "it was silly not to do it", Mr Griffin says: "So he left it up to me."
Although video of the BBC One broadcast with high-quality multi-track audio was kept, many performances from the US were not shown in the UK and so were still missing.
The concert was split between Wembley Stadium, London, and JFK Stadium, Philadelphia - and US broadcaster ABC took Geldof more seriously and made its tapes unusable.
The DVD's producer Jill Sinclair says: "That was what was so heartbreaking because I had no idea that they would be so stupid.
"Not that they thought they were being stupid, they just thought they were following instructions."
Another set of tapes had been given to the Smithsonian Institute - but were lost or stolen.
Eventually, more than 100 Live Aid tapes were tracked down in MTV's archives - albeit with songs cut short by ad breaks and presenters.
Ms Sinclair has not put incomplete songs on the DVD, but the four-disc set, to be released in the UK on 8 November, still clocks in at 10 hours.
Every person who appeared on stage - from backing singers to big stars - has been contacted to get their permission to be on the discs.
The vast majority of artists agreed, saying: "We were there on the day, we wanted to support the cause, we still want to support the cause," Ms Sinclair says.
"We may have been wearing some ridiculous fluorescent yellow shirt or some ludicrous mullet hairstyle - but it's a piece of history and we were part of it."
Madonna had just become a global star when she performed
The only artists to refuse were Led Zeppelin because they said they put in a "sub-standard" performance.
"I did feel cross because I felt like they were letting me down as a fan of Led Zeppelin, I felt they were cheating me," Ms Sinclair says.
"But actually now I'm happy," she says, because Robert Plant and Jimmy Page are giving all royalties from their own forthcoming DVD to Band Aid.
"I could never have imagined they would have come back with something as generous as this," she says.
Technical glitches on the day came when Sir Paul McCartney and Freddie Mercury sang on although their microphones were not working.
Sir Paul re-recorded Let It Be a few days later, while Mercury's vocals have been recovered from other microphones that were working - so both performances are on disc.
'Can't be done'
"[Mercury] didn't know it wasn't being recorded, so he thought he was giving the performance of his life and it seems very hard to not include him," Ms Sinclair says.
As well as the sound improvements, dodgy camera shots have been replaced and the DVD has been finished in record time.
When Ms Sinclair took on the project in May, she says she was "completely on the verge of passing out" when told how soon organisers wanted it.
"They said they wanted it for Christmas and I thought I'm not sure if I can do it for Christmas - and I thought Christmas was in December," she says.
"And then the distributor said 'when we say Christmas, we mean October'. And I felt myself going a bit faint and said 'I don't think it can be done'."
Phil Collins (left) and Sting were among the other stars on the bill
So it has been an "extraordinary achievement", she says - but that has been down to the fact it was Live Aid. "Everybody just pulled out all the stops."
In 1984, when Band Aid's Do You Know It's Christmas? single came out, almost everybody gave their services for free.
This time, artists are still not being paid but DVD company Warner and retailers will take a cut of the £39.99 price. Warner paid a large lump sum to the charity for rights to release the DVD, and will pay more as sales go up.
The DVD is expected to be the must-have gift for every music fan this Christmas - even those who cannot remember the show.
"It seems to me that even very young kids know about it," Ms Sinclair says.
"It's become one of those things a bit like the Second World War - you don't have to have lived through it to know it happened."