The single, a version of the Mariah Carey track released to raise money for the Help For Heroes campaign, debuted at number one yesterday (Sunday), with sales of 313,244 more than half of them physical.

Cowell tells Music Week, "I will predict that the biggest-selling record this year will be the X Factor charity record." And this sentiment is echoed by HMV's Armstrong, who forecasts Hero will even outsell the Christmas single from the eventual X Factor winner.

Hero's weekly ...