Video: X Factor stars sing at Downing St lights switch on

X Factor stars sang for the Prime Minister at the Christmas light switch on in Downing Street.

James, Jahmene and Christopher were joined by judge Nicole Sherzinger - and loads of kids - as they sang outside the famous door to Number 10.

David Cameron was there to see the festive mini concert on his front doorstep.

The X Factor final takes place on 8 December in Manchester.