The History of the Secret Intelligence Service 1909-1949 The first – and only – history of the Secret Intelligence Service, written with full and unrestricted access to the closed archives of the Service for the period 1909–1949. A groundbreaking book, this unprecedented study is the authoritative account of the best-known intelligence organisation in the world. Essential reading for anyone interested in the history of espionage, the two world wars, modern British government and the conduct of international relations in the first half of the twentieth century, MI6: The History of the Secret Intelligence Service 1909–1949 is a uniquely important examination of the role and significance of intelligence in the modern world.