Sovereign nations of importance have found it necessary to maintain army, naval, and air forces to provide for their own defense against possible enemies. The governments in charge of these forces need to keep abreast of the latest intentions, actions, and equipment of their enemies in order to make diplomatic decisions and also to plan military strategy and tactics in case of attack; consequently, they also maintain various intelligence agencies not only to obtain secret information but also to protect themselves from counterintelligence. In Deighton's novels we become acquainted to some degree with the British intelligence system. Of the various agencies, the most prominent ones are Security Service (SS), more commonly known as MI-5, and Secret Intelligence Service (SIS), more commonly known as MI-6. The former protects British secrets from foreign spies and prevents subversive action.

However, it has no powers of arrest and must depend...