On Nov. 25, 1984, dozens of the biggest U.K. musicians — past and present — gathered in Trevor Horn's London studio under the moniker Band Aid to record the now-classic holiday song 'Do They Know It's Christmas?' The idea for this star-studded project arose earlier that same year, after Bob Geldof saw news footage of the famine in Ethiopia. Shaken by what he saw, he enlisted Ultravox's Midge Ure to put together a song, with the goal of raising funds to benefit the country.

While Geldof typically receives the most credit for 'Do They Know It's Christmas?,' Ure was actually the catalyst — from shaping the hushed synth-pop song and recording the original demo, to convincing the Boomtown Rats frontman that the charity song was a viable idea.

"I can absolutely tell you if Midge had said, 'Hmm, I don’t know. Well, let me think about it,' I possibly would not have gone ahead," Geldof said in an interview, "because it would have been too embarrassing right off the bat to be told by somebody, 'Forget it.'"

Famously, the song was recorded and mixed over the course of a grueling 24-hour day — although the song's engineer, Stuart Bruce, noted in a 2011 interview that there was a fairly substantial 24-track backing track with guide music and additional vocals put together prior to the marathon session.

Convincing other artists to come on board and sing on the track was just as easy, for the most part (the notoriously prickly Smiths frontman Morrissey minced no words expressing his displeasure for the project). As a result, the studio gathering featured the biggest U.K. pop stars of the day (members of Bananarama, Duran Duran, Spandau Ballet) and rock 'n' roll luminaries (Sting, David Bowie, Paul McCartney, Adam Clayton and Bono of U2, Genesis' Phil Collins).

Collins played live over the pre-recorded music, and by all accounts was an eager contributor. "It was funny because every time we finished a vocal take, Phil Collins would leap up and shout 'drums!' because he wanted to do his recording," Bruce recalled. "It was funny, because, at the time, Phil was probably one of the most famous singers in the room and was so patient in waiting all day for his turn to do the drums."

When Collins finally got his chance, he was ready. "He bashed around so I could get a sound and then we were ready for a take," Bruce added. "Like most drummers, during the recording he played much louder and distorted the signal, so we had to do it again, but if it wasn't for that, he would have nailed it perfectly first time." The recording wasn't without its hiccups, of course. Culture Club's Boy George notoriously flew in late from the U.S. to sing his part, while the fact that the rock and pop guards were mingling in the same studio — when many of them didn't actually get along — initially made for an odd environment.

Still, the song was an immediate smash: No. 1 on the U.K. charts and selling millions of copies. And the legacy of 'Do They Know It's Christmas?' endures — it was recorded with new groups of musicians in 1989, 2004 and again just a few weeks ago, with Bono once again showing up.

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