Info from subbrit:
Deep bunker built in about 1953 as the Sector Operations Centre for the Metropolitan Sector of RAF Fighter Command. Was probably as big and deep as any of the bunkers built in the Rotor project.
Became the United Kingdom Warning and Monitoring Organisation's Metropolitan Sector HQ (which later moved to Horsham).
Later became the regional Home Office bunker for London, known first as a Sub-Regional Control (1967), and subsequently as a Sub-Regional Headquarters (1973) and Regional Government Headquarters (1985). It came below the Hawthorn Central Government War Headquarters at Corsham and above the four London group controls in the planned hierarchy of wartime government.
In 1993 the bunker was sold to Michael Parrish, who owns the farm where it is located. He has opened it to the public as a cold war museum.
