Standby generator building, RAF Daws Hill bunker compound

Summary

Stand-by generator building, 1980s, formerly within RAF Daws Hill.

Reasons for Designation

The 1980s generator building associated with the bunker at RAF Daws Hill is listed at Grade II for the following principal reasons:

* Contextual interest: although structurally separate, the generator building was vital to the performance of the bunker as United States European Command wartime headquarters at a time of increased nuclear threat;

* Construction: a bespoke 1980s hardened structure, installed in tandem with the new vents above the bunker, demonstrating how the bunker was powered in the strong likelihood of loss of supply from the national grid.

* Group value: together with the contemporary Cold War vents, it is a resonant, visible component of what is otherwise mostly an underground site.

History

During WWII a three-storey underground command headquarters, codenamed PINETREE, was established in the grounds of Wycombe Abbey School which had been requisitioned by the Air Ministry in 1942. The park had been laid out in the mid- to late C18 by Lancelot ‘Capability’ Brown and ‘improved’ later in the century by Humphry Repton. The mansion, now Wycombe Abbey School, was remodelled c 1803-4 by James Wyatt and extended in the late C19 (listed Grade II*). It may lie on the site of a medieval hospital.

Between 1942 and 1945 the headquarters was the nerve centre of operations for United States Army Air Force's daylight bombing offensive over Europe. In the mid-1950s the bunker was refurbished and used by the United States Strategic Command 7th Air Division as its main European planning and operations centre. From about 1970 to 1981 the bunker was unoccupied but from 1982 it was again refurbished as the United States European Command wartime headquarters. During this era the facility also had responsibility for computing the flight paths for aircraft and missiles in the European theatre of operations. It is believed that operational activity in the bunker ceased in 1991 and that it has subsequently been unused.

It was during the 1980s that the bunker was refurbished in line with the policy of Flexible Response, to harden it against nuclear, biological, and chemical attack and the effects of electro magnetic pulse (EMP) released by a nuclear detonation. The decontamination cell was added and most probably the stand-by generator building. Given the lack of decontamination facilities it is likely that during lock down conditions, the generator was unmanned and run remotely. The compound also has its own electricity sub-station and an emergency water supply.

Whilst physically detached from the bunker, the generator building, which was built in the 1980s, was vital to the performance of the bunker at a time of increased nuclear threat.

Most Cold War bunkers took their peacetime power supplies from the national grid, but were equipped with emergency generators that would start-up in the event of a power loss. Usually at this time the generator was integral to the bunker; in this case the bunker, being earlier in date, was not built with a stand-by facility. The structure of the bunker limited how services could be upgraded within it, the new vents and the generator building being the solution.

The method of construction, materials, generator and switch gear were all relatively standard, but given that Cold War bunkers were normally constructed with integral stand-by generation, a bespoke design dug into the hillside was necessary. Like other vulnerable, contemporary structures, it was hardened against nuclear attack, the heavy external doors and the cladding being evidence of this process. Despite the loss of the generators, the generator building demonstrates how the site was upgraded and operated at the time.

Details

Emergency power plant, north of the main entrance. Probably constructed 1980s.

Partly-buried reinforced concrete structure. Rear wall and walls of smaller rooms reinforced internally in steel plates, enhanced protection against nuclear explosion.

Entered from the north through two pairs of double steel doors, which were wide enough for the installation of the plant’s diesel generators, now removed. To the east are separate rooms which housed the plant’s switchgear, which remains intact. Pursuant to s.1 (5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (‘the Act’) it is declared that the surviving plant and the switchgear, which is of standard specification for the period, is not of special architectural or historic interest. Above are two vents that may represent an air inlet and exhaust outlet. There are no decontamination facilities here.

Sources

Books and journals
Cocroft, W D, Cold War Monuments: An Assessment by the Monuments Protection Programme, (2001)
Francis, P, Crisp, G, Internal report, commissioned by EH in Military Command And Control Organisation, (2008)
Cocroft, W, English Heritage Assessment Template in RAF Daws Hill, Buckinghamshire, (2012)

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