He was historical advisor to three BBC series: The Nazis: A Warning From History, War of the Century and Auschwitz.
His most recent books are Hitler 1889-1936: Hubris and 1936-1945: Nemesis, which received the Wolfson Literary Award for History and the Bruno Kreisky Prize in Austria for the Political Book of the Year, and was joint winner of the inaugural British Academy Book Prize; Making Friends with Hitler: Lord Londonberry and Britain's Road to War, which won the Elizabeth Longford Prize for Historical Biography in 2005; and, most recently, Fateful Choices: Ten Decisions that Changed the World, 1940-1941.