The only theatrical movie featuring the British Intelligence Agency G.C.H.Q. (Government Communications Headquarters).
The G.C.H.Q. is a real-life British Intelligence Agency. It provides information assurance and signals intelligence (known as SIGINT) to the British government and armed forces.
G.C.H.Q. was originally known as the Government Code and Cypher School (G.C.&C.S. or G.C.C.S.), when it was first established after World War I. It was known by this up until 1946, when the name was changed to the G.C.H.Q.