The Prime Minister turned on the Christmas lights outside Number 10 Downing Street in the company of a few unexpected guests - the three X Factor finalists.
Amongst them is James Arthur from Saltburn who joined the other two singers, Jahmene Douglas and Christopher Maloney in a rendition of 'Silent Night'.
This year the tree has come all the way from Garrocher Tree farm near Creetown in Dumfries and Galloway.
The farm was selected after winning the annual British Christmas Tree Growers Association competition to find the finest tree in the land.
It will be on display outside the Prime Minister's residence until early January 2013.