Defend the Realm: The Authorized History of MI5

The book offers an in-depth exploration of MI5's pivotal role in 20th-century British history, drawing from newly accessible archives to provide insights into its operations since its establishment in 1909. It examines the agency's evolution and contributions to counterespionage and counterterrorism, highlighting significant events and decisions that shaped national security. By presenting previously hidden information, it sheds light on the complexities and challenges faced by the Security Service throughout its century-long existence.