Summary
A series of rooms contained within the worked-out chambers of a former Bath stone quarry, adapted to an underground government facility in the mid C20: Central Government War Headquarters (CGWHQ). The rooms have been fitted to provide a telecommunications facility, including two telephone exchange operator consoles and a supervisor desk in one area, and a number of rooms to the rear with plant and racking containing the associated equipment required for a telephone exchange.
Reasons for Designation
The GPO Telephone Exchange in the CGWHQ below MoD Corsham is designated as a Scheduled Monument for the following principal reasons:
* Period: the peril from the threat of nuclear strikes that Britain faced during the Cold War is inherent in the installation of this large-scale facility underground to provide telecommunications across the country following a nuclear strike.
* Rarity: this is the only known telephone exchange of its type. Some pieces of equipment, such as the Automatic Telegraph Exchange, are thought to be the only surviving examples of their type.
* Survival: the extensive equipment survives largely intact and in situ, although the PBMX consoles have developed surface damage through damp conditions and isolated incidents of roof fall.
* Group Value: the supreme importance of the CGWHQ site during the Cold War is an unparalleled example of our national military heritage during this era and furthermore represents the systematic use of underground areas for military and industrial use of expansive underground areas during the C20.
* Representative: the sober fitting out of the Bath Stone chamber, with breeze block partitions, is redolent of the grim character of the Cold War era and the functional nature of the area.
History
The Corsham Mines are a multi-layered historic site near Bath, beneath the southern end of the Cotswold Hills in Wiltshire. Quarrying of Bath Stone in the wider area took place from Roman times, and by the C18 Bath Stone had become a highly sought after building material. The opening of the Kennet and Avon canal in 1810, and the subsequent construction of the Great Western Railway in the 1840s, made the transportation of the stone to farther locations easier and cheaper, thereby increasing its popularity. Brunel's cutting of the Box Railway Tunnel, beside the village of Corsham, revealed a rich seam of high quality stone beneath the hills. Intense quarrying followed, leaving a network of quarries with worked-out chambers and air shafts, including Spring Quarry. By the time mining ceased in 1940, there were over 60 miles of tunnels across 3,000 acres, located at depths between 80 and 100 feet below ground.
The Bristol Aeroplane Company (BAC) at Filton, near Bristol was bombed in September 1940. In response, Lord Beaverbrook, of the Ministry of Aircraft Production (MAP), issued an urgent plan to relocate all production below ground, which was endorsed by Churchill. The limitations of time, suitable sites, and wartime resources quickly saw the scheme scaled back to the relocation of Filton's engine plant. In December 1940 four quarries were requisitioned by the Ministry, including Spring Quarry, to the south of the Box Tunnel. It covers a vast 3,300,000 square foot area (or 76 acres). It was intended that BAC would convert Spring Quarry for engine production in 6 months, at an estimated cost of £100,000.
However, the scale of the Ministry's factory construction project was enormous, involving the removal of thousands of tons of rubble stone, the levelling of floors, and the strengthening of pillars and roofs using steel and concrete. Lifts, escalators, and an extensive ventilation system were installed. Furthermore, BAC became doubtful about the practicality of the project, and their involvement was scaled back. The factory was not ready for use by the end of 1942, when German bombing had largely ceased, and the need for the underground factory programme had all but vanished. The MAP factory was reclassified as a shadow factory, and proposed production was switched from the Hercules engine to the less vital Centaurus. By 1945, the factory still fell short of its original specifications, and its cost had risen to many millions. Throughout the war, engine production figures were negligible and the factory closed at the end of the war. MAP itself was abolished in 1946. Spring Quarry was bought by the government in 1954, when the north-east area was allocated for conversion to a secret CGWHQ for use in the event of nuclear conflict.
The first known planning for the dispersed operation of government departments, should Central London be destroyed through enemy attack, was during a sub-committee of the Committee of Imperial Defence under Sir Warren Fisher in 1937. Following the war, it was acknowledged that developments in weapons meant that the government's emergency plans were inadequate. In the light of the huge sums spent developing the MAP factory in Spring Quarry, estimated at £30 million, the Treasury proposed buying the requisitioned quarry for use as a citadel for future emergencies. However, the quarry was not bought from the Bath & Portland Stone Company until April 1954, along with 100 acres of land above ground. In 1957 the plans for the emergency headquarters were finalized; the site was intended to provide a safe haven from which the work of Government could continue. From here, the reconstruction of the country following a nuclear attack would be overseen. It was designed to accommodate up to 4,000 military and government staff, including the Prime Minister and key cabinet officials. Occupants would be sealed underground for 30 days and coordinate with Regional Seats of Government (RSGs) around the country, meaning that extensive communications and welfare infrastructure was needed.
Work began in 1957 with the construction of a reinforced concrete wall separating the CGWHQ area from that part of Spring Quarry used by the Admiralty. A buffer zone between the two was lined by a concrete block partition and solid rock pillars, sealing the Central Government side. Three blast doors were installed. New ventilation shafts were created and reinforced. Internal areas were divided by concrete block or, in some cases, with red brick. The northern parts of the main roadway through Spring Quarry (now called East/ West Main Road) were converted to a large telephone exchange, stores and plant rooms. Those to the south were offices and accommodation for the Government departments and War Cabinet, a communication centre, and an extensive canteen and kitchen facility. Most of the major building works were complete by April 1959.
The installation of the government citadel, codenamed Subterfuge, in 1954-9, stalled in the summer of 1959 when the Civil Defence budget was cut. However, by 1961 the GPO Telephone Exchange, known as Woodlands, was complete. It was installed by GPO and RAF engineers and was of vital importance to the project, communication being key to the survival and restoration phases following nuclear attack. The construction of a number of RSGs across the country had begun, and these would liaise with Corsham's Central Seat of Government, via Woodlands, following the evacuation of London. Additionally, there were circuits for communication overseas with allied and commonwealth governments, NATO centres and British embassies. The scale of the telecommunications facility was only matched by that in Whitehall, and it is thought that 1,000 staff would be required to operate the system.
The Exchange system appears to have been operational and regularly tested until 1992. The CGWHQ complex was never needed or used for its intended function, and was reduced in capacity over a number of phases during the late C20. The site was de-commissioned in the early 1990s. It was de-classified in 2004.
Details
PRINCIPAL ELEMENTS: the GPO Telephone Exchange, or 'Woodlands', is divided into separate operational areas over 5419 square metres. It comprises large manual switchboards, automatic telegraph and telephone switching and comprehensive transmission facilities. These combine to form a large telecommunications facility. Sub-areas within have been separated by inserted concrete block walls, and stand on two levels.
DESCRIPTION: the principal operational area of the GPO Telephone Exchange is in Rooms 82 and 83, the Manual Switch Board Rooms, to the immediate north of East Main Road. Room 83 contains two multi-position telephone operator switchboards. 'Suite 1' has 40 positions, with 15 cord circuits each; and 'Suite 101' with 14 positions and 8 circuits each. The boards are constructed of mahogany. At the west end of the room is a directory enquiry desk with four positions, and a supervisor's desk. The desks are in a rapidly deteriorating condition. Further west, stairs lead to an upper level, Room 82. The areas to the north of this upper level (Room 81 and part of Room 68) are open with supporting columns and tiled flooring. While they form part of the Exchange facility, they have never been equipped and are not considered part of the operational area and are not included in the scheduling.
The rooms to the north of Room 83 contain metal telecommunication frames with equipment, plant rooms, engineers work stations and workshops. Room 72 is the Automatic Telephone Exchange and contains a metal frame with installed telecommunications equipment. Room 71 contains the large Main Distribution Frame (MDF), a substantial feature that is largely unfilled frame with travelling timber ladders to access the upper parts. The MDF functions as the termination point for cables in the Exchange. Further equipment in the facility includes an Automatic Telegraph Exchange in Room 68. An Engineer Test Desk, stands in the north-east corner of Room 68, with two positions.
Neighbouring areas contain the necessary plant to run the facility, including Air Compressors (Room PR2), an Air Handling Unit (Room PR1), and a Telephone Repeater Station. The TRS and TGH Power Room (Room 70) contains a motor alternator, regulatories and a standby generator that could run the whole of Woodlands. Other fixtures include light fittings showing the Exchange status, with attached bells and Public Address loudspeaker (Room 70). To the far north are store areas and the perimeter walls of the CGWHQ. Across the GPO Telephone Exchange, different areas are delineated by different coloured floor tiles.
The non-operational part of the Exchange, including extensive areas which were never fitted with equipment but were allocated for potential expansion of the facility, are excluded from the scheduling, although they represent an interesting context to the areas of higher national importance. Otherwise, the designated area extends to 1m around the designated boundary, and 1m above and below. All above ground structures are excluded from the designation.
