Government Communications Headquarters

{{subpages{{ Britain's Government Communications Headquarters (GCHQ) is responsible for national signals intelligence and communications security. It is a direct descendant of the Second World War organization, the Government Code and Cipher School, which was responsible for the ULTRA cryptanalysis of the Enigma machine.

Under a still-classified "UKUSA Agreement", there is substantial sharing of signals intelligence collection and product among the Australian Defense Signals Directorate (DSD), Canadian Communications Security Establishment (CSE), New Zealand Government Communications Security Bureau (GCSB), and the United States National Security Agency (NSA). There may be another information-sharing agreement called ECHELON.

While the WWII GCCS was under the the Secret Intelligence Service (SIS), GCHQ reports to the Foreign Secretary and work closely with the SIS (commonly but incorrectly called MI6), Security Service (MI5) and military intelligence.

Often called "Bletchley Park" after the WWII location, the current GCHQ main facility is in Cheltenham. There is, however, an "Enigma Tavern" in the town of Bletchley Park.