English Heritage’s most modern, most unusual and perhaps most spine-chilling site,‘No.20 Group Royal Observer Corps HQ’ is the semi-subterranean bunker which would have monitored nuclear explosions and fallout in the Yorkshire region. In service between 1961 and 1991, the Bunker’s control rooms display ‘colourpsychology décor’ together with original monitoring and communications equipment.

Decontamination rooms with air filters and special sewage ejectors were intended to seal off the 60 strong workforce from the devastated outside world. A guided tour by EH staff enhanced by a striking 10- minute film and interpretation with the aid of original Corps members, tells the story of the Cold War’s ‘Mutually Assured Destruction.