Royal Observer Corps (ROC) monitoring post

Summary

ROC and UKWMO monitoring post, to a standard design of 1956 by the Air Ministry Works Department and built between 1958 and 1961.

Reasons for Designation

The former Royal Observer Corps monitoring post at the former Dunsfold Airfield, one of a network of subterranean posts designed to monitor radioactive fallout following a nuclear attack, is listed at Grade II for the following principal reasons:

Architectural interest:

* As a good example of a standard design that is an architectural representation of the threat of nuclear attack during the Cold War;

* For the excellent state of preservation retaining its full complement of fixtures and fittings;

Historic interest:

* For its association with Dunsfold Airfield with its links to the Berlin Airlift, a defining event in the Cold War, and subsequently as the site of military aircraft development during the Cold War period.


Group Value:


* With the Grade II listed engine running sheds (National Heritage List for England 1446621) and V/STOL blast grid (NHLE 1447246) for their Cold War associations.

History

Dunsfold was constructed as a military airfield in 1942 for the Royal Canadian Air Force. Initially it was home to four squadrons of Tomahawks and Mustangs, tasked with training and reconnaissance. By August 1943 it had become a bomber base, supporting Mitchell bombers on European missions, and by 1944 the airfield had three runways and accommodation for over a 1,000 personnel. In 1945 it supported Operation Exodus, which repatriated Allied prisoners of war back to their homeland. By 1948, Dunsfold, as the principal operating base of the private air charter company, Skyways Ltd, was supporting the Berlin Airlift, helping to deliver vital supplies by air to the blockaded city. In 1950 the site was sold to Hawker Siddeley, who developed and manufactured jet aircraft, including the Hunter and Harrier. The airfield is now (2017) in separate private ownership.

The Royal Observer Corps (ROC) was a civil defence organisation, mainly staffed by civilian volunteers. It traced its history back to the 1920s when a system of aircraft reporting was developed which formed part of the country's air defence, a role it performed during the Second World War before being stood down in May 1945. It was re-instated in 1948 to meet the new threat posed by the Cold War and in 1955 became part of the newly formed United Kingdom Warning and Monitoring Organisation (UKWMO), charged with the task of reporting nuclear explosions and the monitoring of the resultant spread of radioactive fallout in the event of nuclear attack. This was facilitated by the construction of a national network of 1518 underground monitoring posts (1026 being in England) organised into clusters of 3-4 posts which then reported to regional Group Headquarters. These replaced above-ground posts, usually housed in pre-fabricated 'Orlit' posts, and reflected their new role. In 1968 the number of maintained posts was halved. In 1991, with the end of the Cold War, the service was stood down and the posts closed.

Construction of the system of monitoring posts began in the late 1950s and was largely complete by 1965, although some new posts were built in the 1970s. Where possible, the underground monitoring posts were located on the sites of old visual reporting posts and were evenly distributed across the country. The posts had three main tasks: to confirm that a nuclear attack had taken place and its location; to estimate its power; and to monitor the passage of radioactive fallout. They were built to a standard design to accommodate a staff of three and to be self-sufficient for 21 days. The posts were buried below the ground surface and covered with an additional compacted earth mound designed to provide protection from blast and heat, and to reduce radiation penetration.

The ROC monitoring post at Dunsfold appears initially to have been known as Cranleigh (after its original Second World War location) but seems to have subsequently been known as Dunsfold 52. The site was moved from Cranleigh to Dunsfold between 1952 and 1958 and by 1961 is known to have been placed underground. The post, which reported to the Group Headquarters at Horsham, had the designation 2/P4 (Post number 2 in P cluster of 4 Group) in 1952 but had been re-designated 2/G1 by 1968 (Dobbins, 2000 p293). It continued to be operational until September 1991.

Details

ROC and UKWMO monitoring post, to a standard design of 1956 by the Air Ministry Works Department and built between 1958 and 1961.

MATERIALS: reinforced concrete with a compacted earth covering.

EXTERIOR: located on the south-west boundary of Dunsfold airfield it appears as a rectangular, flat topped, vegetation covered mound with a raised entrance shaft towards one end and a smaller, raised air vent towards the other end. The concrete entrance shaft has a counterweighted steel hatch and adjacent to it are metal ventilation louvres and the metal fitting for the Ground Zero Indicator (a pinhole camera device for detecting the direction and altitude of nuclear explosions). A stepped brick mounting block adjoins the shaft.

INTERIOR: the 4.6m deep vertical entrance shaft is 0.6m square with a steel access ladder. At the foot of the shaft is a drainage sump with a metal grill. The sump retains its wall-mounted rotary hand pump. The shaft gives access via two timber doors to a small closet for a chemical toilet and to the monitoring room which measures 4.6m by 2.3m. The walls and ceiling of the monitoring room are clad with textured polystyrene tiles (probably a later addition to attempt a degree of insulation). The room retains its rubberised flooring. Along one wall are two crude fitted wooden tables, either side of a cupboard, and some fitted shelves. The walls retain the metal and plastic trunking and, at the far end, a metal ventilation flue shutter. The fittings remain for the fixed survey meter probe (which allowed the recording of external gamma radiation without venturing outside) and the bomb power indicator (which measured the size of a nuclear explosion).

Sources

Books and journals
Dobinson, C, Twentieth Century Fortifications in England Volume 11 and appendices: The Cold War, (1998), 293
Cocroft, WD, Thomas, RJC, Cold War: Building for Nuclear Confrontation 1946-1989, (2003), 174-196

Websites
Dunsfold Airfield History Society - Skyways 1946-1950, accessed 19 June 2017 from https://dunsfoldairfield.org/skyways/#more-577

End of official list entry

All text content is available under the Open Government Licence v3.0 , except where otherwise stated. Any supplied maps are © Crown Copyright [and database rights] 2026 OS AC0000815036 and may not be reproduced without permission.

Print the official list entry