MI-5

formally Security Service intelligence agency charged with internal security and domestic counterintelligence activities of the United Kingdom. It is authorized to investigate any person or movement that might threaten the nation's security. MI-5's earliest antecedent was a secret service formed in 1569 by Sir Francis Walsingham, who later became secretary of state to Elizabeth I. The need for centralized control of intelligence functions was first expressed early in the 20th century. MI-5 was formed in 1909 to identify and counter German spies then working in Britain, which it did with great effect. It was placed under the command of Vernon Kell, then a captain in the British army. Kell retired as a major general in 1924 and was later knighted, but remained in charge of the agency until 1940. (The MI-5 label developed during this period because it was then section five of military intelligence.) MI-5 is responsible for domestic counterespionage but has no powers of arrest, which devolve instead on Scotland Yard.