Now owned by English Heritage and managed as a tourist attraction, the York Cold War bunker was opened on 16 December 1961 as the protected headquarters of No. 20 Group of the Royal Observer Corps (ROC). The ROC, part of the United Kingdom Warning and Monitoring Organisation (UKWMO), was a volunteer civilian organisation administered by the Air Ministry and originally associated with the Royal Air Force. In 1954, the ROC was given the nuclear reporting role and tasked with gathering data on any nuclear explosions and issuing appropriate warnings to civilian and military authorities. To carry out this role, the Ministry of Works constructed a series of 31 nuclear-resistant bunkers and over 1,500 underground monitoring posts throughout the country from the late 1950s. York's bunker was built at the height of Cold War tensions when fears of a Soviet takeover of West Berlin and the 1962 Cuban Missile Crisis raised the risk of a nuclear war.
The York bunker is a three-storey, rectangular, waterproofed structure made of reinforced concrete and built on government-owned land formerly occupied by an orchard. It is partially subterranean, with part of the bunker located below ground level and the remainder buried under a three-foot deep layer of earth. Although not designed to survive a direct hit, the bunker's thick earthen covering would have offered increased protection against the blast and heat of a nuclear explosion and reduced the effects of radiation. Only the entrance block and the stairs leading to it, as well as the emergency escape hatch located at the other end of the earthen mound, were exposed.
In the event of a nuclear attack, the area in the immediate vicinity of a bomb explosion would have been obliterated by the bomb's flash, blast (shockwave and sound), heat, and initial radiation, while radioactive fallout would have caused thousands of additional casualties tens or even hundreds of miles away. Additionally, while not affecting human health, the electromagnetic pulse created by a nuclear detonation would have caused massive induction surges in unprotected electrical circuits, destroying electrical and communications equipment. As the lethal effects of fallout could be minimised through sufficient advance warning of the approach of the radioactive plume generated by a nuclear bomb detonation, the ROC staff manning the bunkers would have monitored and assessed nuclear explosions and associated fallout plumes and their path and intensity, issuing appropriate warnings to government headquarters, home defence forces, and neighbouring counties.
The bunker's peacetime complement was three full-time personnel, headed by the Commandant, a volunteer civilian responsible for the operational functioning of the bunker and the group. A Deputy Commandant was responsible for equipping the group and its practical administration. ROC volunteers attended evening and weekend training sessions and participated in two major exercises per year. During exercises or in an emergency, each bunker would be fully manned by up to 60 men and women, comprising ROC volunteers, British Telecommunications engineers, and Home Office nuclear scientists. The staff would be split into three watches (duty, stand-by, rest) and expected to work in a nuclear environment for up to two weeks. Although the ROC was prepared to call up its volunteers to man the bunkers and associated monitoring posts during the Cuban Missile Crisis, the order was never given as diplomacy defused the standoff between the United States and the Soviet Union. Indeed, despite periods of intense Cold War tension, the ROC was never ordered to fully man its nuclear monitoring system.
With the end of the Cold War and the collapse of the Soviet Union, the ROC was stood down on 30 September 1991. A single full-time ROC officer, assisted by an observer and a civilian secretary, remained on duty at the No. 20 Group bunker at York to oversee the closure of the bunker and its monitoring posts. The York bunker was finally closed on 31 March 1992 and left to deteriorate for eight years. In 2000, the bunker was acquired by English Heritage and, following restoration work, opened to the public.
Photos taken on 21 April 2024
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| The York Cold War Bunker is located on Monument Close, a short dead-end road in one of the city's residential neighbourhoods. This protected headquarters structure was built partially underground and covered with three feet of soil to defend against blast and heat damage, as well as radiation from a nuclear blast. |
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| Tourists wait at the foot of the reinforced concrete entrance block for the 10:00 guided tour of the bunker to commence. |
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| Stairs lead up to the entrance block, originally painted white, with the rubber-sealed, gas-proof blast door open to receive visitors. All large openings in the entrance block were fitted with external steel baffle plates to deflect blast. Inside the entrance block were the radiator room, the aerosol filter chamber (for filtering radioactive particles from air circulated into the bunker), a machinery access space, an emergency water tank, and decontamination rooms where Royal Observer Corps personnel would disrobe, shower to remove any radioactive particles, and don clean clothing before proceeding into the bunker proper. The water-cooling tower sits atop the roof on the left. The telescoping steel radio mast (to the right of the stairs) was a later addition to the bunker and ensured that communications could be maintained even if local telephone circuits were knocked out. |
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| Just inside the blast door, on the right, is the radiator room. The radiator installed here dispersed heat from the bunker's diesel generator. As the radiator would have been cooled using radioactive air from outside following a nuclear attack, the radiator room was sealed and sited well away from the bunker's principal rooms. The radiator room remains configured as it was when the bunker was closed in March 1992. |
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| Descending from the entrance block into the subterranean bunker. |
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| The corridor on the mid-level of the bunker. Off the corridor are entrances to the plant room, operations room, sewage ejector unit room, kitchen and canteen, telephone exchange, toilets, dormitories, and officers' room. The door to the emergency escape hatch, a counter-weighted hinged steel manhole cover designed to resist a 30-ton pressure wave, is at the end of the corridor. |
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| The plant room contains the electrical generator and heating & air conditioning equipment required for the bunker to function in the event that the municipal electrical grid was knocked out. The generator would activate automatically if mains power was lost. With its own water tank and external underground diesel fuel tank for the generator, the bunker could be self-sufficient for up to 30 days. Nevertheless, the air quality inside the bunker would have been affected if the generator was used for an extended period. The plant room is displayed as it existed when the bunker was closed in March 1992. |
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| The air compressors in the plant room, used to circulate air throughout the bunker. The ventilation system could be operated in four modes: Normal (outside air mixed, cooled, and circulated); Modified Normal (outside air circulated without being cooled to save water); Recirculation (internal air reused); and Filtration (outside air drawn through filters to strip dust and radioactive particles). After a nuclear attack, the bunker would have relied on recirculated air for as long as possible before switching to Filtration mode to draw in outside air through the filters and expel foul air before switching back to Recirculation mode. This process was designed to minimise exposure of the bunker's staff to air contaminated by radioactive fallout. |
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| The sewage ejector unit room houses the equipment required to pump waste water and sewage from two holding tanks into the municipal sewage system. Because the bunker was constructed below the level of municipal sewage mains, the bunker's wastewater had to be forced up and out to the mains using a blast of compressed air from a pressurised cylinder. This was done automatically when the holding tanks reached capacity. The compressed air was replenished using the automatic compressors located in the plant room. |
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| The small kitchen, equipped with a catering oven, hot plate, electric cooker, toaster, and water heater, was used to prepare meals for the bunker's staff. Although the peacetime permanent complement was three persons, in the event of a nuclear attack, the bunker would have been manned by up to 60 people. As such, supplies would have been severely limited at full manning and the Royal Observer Corps even published its own cookbook with creative recipes using the limited range of available ingredients. Adjacent to the kitchen is the canteen, which was the only place in the bunker where staff could relax. The canteen was a multi-functional room used for both eating and training, with tables and chairs stacked at the sides of the room when not in use. Today, tours of the bunker commence with a short film on the Cold War shown in the canteen. |
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| The upper gallery of the operations room, the heart of the bunker. Post Display Plotters here in the gallery would have recorded information on nuclear bursts received from the network of outlying monitoring posts via phone, teleprinter, and radio. The information would have been written on the post-display boards in front of each plotter's position and the boards then rotated every five minutes to be seen by the bunker's senior staff in the lower operations room, below. Data from at least three monitoring posts would have been plotted on the triangulation table to accurately determine the ground zero of any nuclear bomb, the power of its detonation, and whether it was an air-burst or ground-burst explosion. Studies by the UK Home Office in the early 1950s determined that under normal weather conditions, the radioactive fallout plume produced by a 10-megaton thermonuclear bomb dropped on Birmingham would reach the Norfolk coast in nine hours. |
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| The lower operations room, as seen from the gallery. During a crisis, the Duty Controller and Senior Warning Officers would have recorded and monitored information on a nuclear attack, passing this information on to other government bunkers and civil and military authorities. The clear plexiglass screen, known as Display A, was used to show the current situation, with plotters updating fallout information using grease pencils and writing in reverse from behind the screen so that the senior officers could keep track of developments. Other screens in the lower operations room displayed the cumulative situation (Display B), the European situation map (Display E), and the United Kingdom situation map (Display T). |
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| Another view of the lower operations room, where the senior officers would have sat at the command table during a crisis. Fallout data was initially recorded on fallout boards and eventually transferred to the dose log charts which recorded radioactivity levels over time, as well as Displays A and B. As a nuclear attack unfolded, the accumulating data would have been constantly communicated by the 'Tellers' to the Midland Sector Control at Fiskerton, near Lincoln, as well as the adjacent Group Headquarters, and various other recipients. The bunker's communications equipment was located in a sound-proof room below the operations room's gallery. |
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| The triangulation table for plotting data on nuclear explosions received from at least three monitoring posts in order to accurately plot the location of the detonation. To the right, displayed on a small table, is the white cylindrical ground zero indicator, a pinhole camera used to calculate the position of a nuclear explosion and originally mounted on the bunker's roof. Mounted on the wall on the right, above the telephone, is the bomb power indicator. The air pressure wave created by a nuclear explosion would have hit a steel baffle plate at surface level and travelled down a steel pipe to register on the dial of the bomb power indicator. |
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| The display unit of the Atomic Weapons Detection Recognition and Estimation of Yield (AWDREY) remote sensing device. The AWDREY system was installed in this bunker and 12 other Royal Observer Corps headquarters in the late 1960s when it became clear that a nuclear attack on Britain could be launched with little advance warning. AWDREY's sensor was mounted on the bunker's roof and, in the event of an attack, the system would automatically have transmitted data about the explosion to all other group and sector headquarters. |
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| The women's dormitory. This room contains six two-tiered bunk beds with a capacity for 12. A smaller men's dormitory could accommodate eight male staff. Since the bunker's staff in an emergency could number between 50 and 60, 'hot bunking' was necessary and staff used whatever beds were not occupied. Given the cramped conditions, personal possessions could only be stored in suitcases and bags on the shelves above the beds. The dormitories had dimmer switches to keep lighting low for those trying to sleep; however, sleeping in the bunker would have been difficult during periods when stale, warm internal air was being recirculated. |
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| The telephone exchange. When built, the bunker had a manual telephone switchboard manned by volunteer General Post Office operators. A computer-controlled SX2000 digital private automatic branch exchange was installed in the 1980s, with direct lines to police stations to issue nuclear fallout warnings to the public. A cypher message switching system was also introduced to speed data transfer rates. Since a telephone network's copper wires are vulnerable to blast damage and the electromagnetic pulse generated by a nuclear detonation, cables were laid underground wherever possible and the SX2000 exchange was housed in a shielded cabinet. In the event that the telephone system was knocked out, the bunker's radio room was equipped with Very High Frequency (VHF) radio systems connected to the telescoping radio mast mounted to the exterior of the bunker's entrance block. |
