Stars including One Direction, Emeli Sande and Ed Sheeran are going into the studio later to record a new version of the Band Aid charity single.
Ellie Goulding, Sam Smith, Bastille, Chris Martin and Bono are also among the musicians who will sing on the reworked Do They Know It’s Christmas?
It comes 30 years after the original raised £8m for famine relief. This time, the funds will help fight Ebola.
The new song will get its first play on ITV’s X Factor results show on Sunday.
It will be made available to download at 08:00 GMT on Monday, priced at 99p. A CD version costing £4 will be released three weeks later with a cover designed by artist Tracey Emin.
Saturday’s recording session will take place at the Sarm studios in west London, the same venue where stars like Wham!, Duran Duran, Sting and Status Quo recorded the original in 1984.
This time, fans will be able to follow the recording session on an official app, which will stream live footage from the studio.
That footage will also form the basis for the music video, which will be edited in “record time” in order to be shown on The X Factor at 20:00 GMT on Sunday.
The record is being produced by Paul Epworth, who has masterminded hits by the likes of Adele and One Direction.
The song will not be made available on Spotify and other music streaming services until January.
Source:: BBC Entertainment