Fox's rebellious nature led to difficult times at Harrow School and the Royal Academy of Dramatic Art (RADA). His first break into film was in the horror-thriller The Hole (2001), which he followed up with a part in Gosford Park (2001). After playing a number of German and British soldiers, his performance in Colditz (2005) was noticed. This led to his being offered the role in Lewis, six series of which have been produced and aired between 2006 and 2012.