Kelvedon Hatch, just outside London, was one of Britain's top secrets during the Cold War. Built in the 1950s into the hillside, this colossal underground bunker was to house more than 600 people and to keep them going for up to 3 months – had Britain come under a nuclear attack from Moscow.
The Royal Air Force was to control from here its response to a nuclear attack. It was also to become the Headquarters of an emergency Central British Government, including the Prime Minister's office.
© Velislav Radev