This ward at the No 1 Australian Auxiliary Hospital in Middlesex, England, was decorated with a Santa Claus and a large map of Australia on the rear wall and the word "HOME" on it in large letters. However, it does not look as though the festivities have yet started.
In pictures: Eleven ways soldiers celebrated Christmas during World War I - ABC News (Australian Broadcasting Corporation)
StateLibQld 2 66852 Battle of Messines. Anzac Field Dressing Station scene 7 June, 1917
File:StateLibQld 2 66852 Battle of Messines. Anzac Field Dressing Station scene 7 June, 1917.jpg - Wikimedia Commons