Born in Yorkshire, attended Martborough and Cambridge, where he discovered acting on a lark and abandoned a planned career as an architect. Mason's talent for playing protagonists of a decidedly hard-bitten or melancholy stripe brought him from these minor films to a position as one of Britain's major film stars of the Forties.

War film buffs know him best in his two portrayals of Rommel and as Colonel Brandt in Cross of Iron. James Mson is remarkable in that even though he had many military screen roles, he was an avowed pacifist. He refused to perform military service during World War Two, a stance that caused his family to break with him for many years.

His war/historical film credits include Fire Over England, The High Command, The Desert Fox, The Desert Rats , Julius Caesar, Genghis Khan, The Blue Max, and Cross of Iron