In his late 20s, Demange attended the National Film and Television School on a scholarship from Disney. He secured a deal with ICM Partners on the basis of his graduation film, which led to him directing several episodes of the television series Secret Diary of a Call Girl (2007). He next directed the zombie horror series Dead Set (2008), which was nominated for a BAFTA Television Award for Best Drama Serial. For his direction of Channel 4's Top Boy (2011), a gang drama set in Hackney, Demange received a nomination for a BAFTA Television Award for Best Director, while the serial was nominated in the category Best Mini-Series.
Demange made his directorial film debut with '71 (2014), which stars Jack O'Connell as a soldier deployed to Belfast at the height of political violence in Northern Ireland. '71 premiered in competition at the Berlin International Film Festival and went on to receive critical acclaim. Demange won the British Independent Film Award for Best Director and was nominated for the BAFTA Award for Outstanding Debut by a British Writer, Director or Producer. Demange has also been hailed as a promising new voice in British filmmaking.
