page_title: Royal Observer Corps
section_title: Restructuring and reconstruction
hierarchical_section_title: Royal Observer Corps / The Cold War / Restructuring and reconstruction
caption_attribution_description: English: York ROC Bunker, owned by English Heritage and open to the public.
context_page_description: The Royal Observer Corps was a civil defence organisation intended for the visual detection, identification, tracking and reporting of aircraft over Great Britain. It operated in the United Kingdom between 29 October 1925 and 31 December 1995, when the Corps' civilian volunteers were stood down. Composed mainly of civilian spare-time volunteers, ROC personnel wore a Royal Air Force style uniform and latterly came under the administrative control of RAF Strike Command and the operational control of the Home Office. Civilian volunteers were trained and administered by a small cadre of professional full-time officers under the command of the Commandant Royal Observer Corps; latterly a serving RAF Air Commodore.
context_section_description: In 1962, the forty ROC Groups were reorganised and reduced in number to thirty-one, with a further reduction to twenty-five taking place in 1968. Service age limits of 16 to 65 were introduced, with service after the age of 65 only occurring where replacements could not be recruited, subject to annual review, and where appropriate medical certificates could be provided. (Some individuals acting as wartime post observers had served well into their seventies and eighties, although wartime centre observers had been forced to retire at fifty.)
  To enable the ROC to operate in a nuclear environment, changes were necessary to both centres and posts in order to provide protection against blast effects and radiation from nuclear bursts. It would also now be necessary for control centres and observation posts to be occupied for a period of between seven and twenty-one days following any nuclear event. Between 1958 and 1968 a countrywide building programme resulted in a network of 1,563 underground monitoring posts, approximately eight miles apart, distributed throughout England, Scotland, Wales and Northern Ireland, at an estimated cost of almost £5,000 each. The posts were excavated to a depth of twenty five feet, a monocoque reinforced concrete building was cast and bitumen tanked (or waterproofed), before the whole structure was covered by a compacted soil mound. Entry was facilitated by a steel ladder in a vertical shaft leading to a single room, providing accommodation for three observers to live and work, with a separate toilet compartment with chemical closet. Air was circulated from grilled ventilators at both ends of the post and electricity was provided by a crated 12 volt lead–acid battery, charged occasionally by a portable petrol electric generator. New instrumentation detected the peak overpressure from any nuclear burst, together with photographic indications of the burst location and size, plus resulting levels of radiation. Conditions in these spartan posts were cramped, cold, and in some cases damp.
  ROC centres were renamed as Controls and provided with bomb proof nuclear protected buildings. A small number of these were converted from suitable pre-existing Second World War anti-aircraft operations rooms (AAORs), with the remainder specially constructed as above ground or semi-sunk blockhouse buildings. These were constructed to a standard layout, dependent upon the subsoil composition at the construction site. Controls provided living and operational accommodation for up to a hundred observers and UKWMO warning teams. Included in the centre layout were male and female dormitories, kitchen and canteen provision, life support systems and decontamination facilities, a communications centre and a split level central operations room with balcony positions.
  In the vicinity of each control was a compact, brick built shack called the Radiac Store, which housed approximately 20 nuclear radiation sources in the form of milled metal discs. These discs, with strengths of 0.5 röntgen, 1 röntgen, 5 röntgens and 10 röntgens, were securely stored in lead-lined containers. Discs had to be audited monthly which entailed an ROC officer physically counting the discs into the palm of their bare hands, with the results being recorded in a log book. (This task was usually achieved with a degree of haste). Discs were used to calibrate and check the stocks of radiac instruments and for simulated live-training using such instruments. In practice, Health and Safety at Work regulations introduced in the 1970s resulted in radioactive sources being rarely if ever used, and as a result they seldom left the radiac store. Discs were finally withdrawn from service and returned to Aldermaston during the mid-1980s, with the last exercise involving such live radiation sources taking place at RAF West Raynham in 1980, during the annual ROC summer training camp.
caption: No.20 (York) Group Control: A fully restored example of a semi-sunken bunker, now owned by English Heritage and open to the public.[4]
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