X Factor bosses to keep winner's Christmas single 'under wraps' X Factor bosses are aiming to keep the winner's single secret until it is performed at the final. In previous years the tunes have leaked out in advance of the ITV1 show's climax, but this time bosses are aiming to keep a lid on the chosen tracks. They are returning to the formula they used in 2010 where each of the finalists has recorded a different track, unlike some years where they have all prepared versions of the same song. In 2011, they all worked on versions of the Damien Rice track "Cannonball," which series victors Little Mix took to the top of the charts. Many of those who have had to be made aware of the finalists' chosen tunes have been sworn to secrecy. Last week show bosses confirmed the winner's track will, for the first time, be a charity single in aid of Together For Short Lives. It will be released as a download shortly after the winner is crowned during Sunday night's finale in Manchester, and then on CD by midweek. Programme chiefs are releasing the winner's single a week earlier than usual, which means the song is more or less ruled out of contention for the Christmas number one, which will be decided a week later. Bookmaker William Hill says the favourite to clinch the seasonal top spot is a charity cover of the Hollies' hit "He Ain't Heavy, He's My Brother." The track, released under the name of The Justice Collective, features Sir Paul McCartney, Robbie Williams, Melanie C and Holly Johnson.