Some of the biggest stars in music are gathering today to record a new version of the Band Aid charity single, to raise money for the victims of Ebola.
Stars including One Direction, Emeli Sande, Rita Ora, Chris Martin and Bono will sing on the new version of Do They Know Its Christmas?
Arriving at the Sarm studios in west London today, One Direction's Niall Horan told the BBC, "Hopefully it gets to number one and raises a lot of money for a really worthy cause."
He said that it was a "privilege" to have been invited to contribute to the single by Sir Bob Geldoff, who was behind the original version 30 years ago.
Geldof, who co-wrote both the original and the new version with Ultravox frontman Midge Ure, said that money raised would go towards the fight against Ebola, which he called a "filthy little virus" that renders its victims "untouchable".
He said that the disease that has killed thousands in west Africa had managed to cause such devastation to communities "because they're extremely poor, which is radically unacceptable", adding: "It makes me sick and makes me angry."
Other artists taking part in the recording include Ed Sheeran, Sam Smith, Underworld, Elbow, Disclosure, Jessie Ware, Fuse ODG, Sinead O'Connor, Angelique Kidjo, Paloma Faith, Queen drummer Roger Taylor, Clean Bandit and Foals.
And there are rumours that David Bowie may feature on the single.
The new version will have its first play after ITV's X Factor results show on Sunday night, meaning the stars will be racing against time to complete the single, and producers edit a video.
Band Aid 30 is being recorded in the same venue as the original 1984 single, which raised more than £8m for the victims of famine in Ethopia, and featured some of the biggest stars of the day, including Duran Duran, Status Quo and Sting.
The single led to the Live Aid concerts, which raised more than £150m for charity.
The lyrics of the original song have been changed in the new version.
The original words: "Where the only water flowing is the bitter sting of tears" have been replaced with "Where a kiss of love can kill you and there's death in every tear".
And the words: "Well tonight thank God it's them instead of you" have been changed to: "Well tonight we're reaching out and touching you."
Fans can follow the recording on a special app which will stream footage live from the studio.
The single is being produced by Paul Epworth, who works with stars including Adele and One Direction.
Chancellor of the Exchequer George Osbourne has also announced that VAT on purchases of the single will be waived, to allow 100% of proceeds to go to charity.
Band Aid 30 will be available to download at 8pm GMT on Monday, priced at 99p. A CD version costing £4 will be available three weeks later, with a cover designed by Tracy Emin.
It will be available on streaming music sites from January.
This is the fourth time the song has been re-recorded, with other versions having been released in 1989 and 2004.