Summary

A part-inclined and part-vertical shaft, probably originally constructed to provide ventilation in Spring Quarry, Corsham in the C19. The shaft was modified and an escalator was inserted in c1943, to provide pedestrian access between the surface and the newly-installed Bristol Aircraft Factory in Spring Quarry. The upper, vertical section of the shaft was rebuilt and strengthened in c1961 as part of the construction of the Central Government War Headquarters (CGWHQ) in Spring Quarry.

Source: Historic England

Details

PRINCIPAL ELEMENTS: a part-inclined and part-vertical shaft providing pedestrian access from ground level down to Spring Quarry, comprising an escalator, rising the length of the inclined shaft, with an open-well stair rising the remainder of the distance to ground level, via a vertical shaft. The inclined shaft rises from approximately 35m below ground, terminating at ground-level via vertical shafts adjoining the incline, on an east-west orientation

DESCRIPTION: the base of the escalator is reached via a painted brick foyer and rises through a vaulted, vertical-walled, reinforced-concrete tunnel. The original wooden treads on the escalator have been removed and replaced with anti-slip surfacing. There are tubular metal handrails running its length. The running machinery is exposed. Below and to the right of the escalator a set of concrete stairs rises up the sloped shaft, providing access for maintenance of the machinery. Lighting and electrical cabling are attached to the side walls.

The top of the escalator terminates within the first of two adjoining circular shafts. Circular rooms below and above the escalator head contain the machinery to drive the escalator, and Crompton-Parkinson power generation equipment. The adjoining shaft contains a wide, open-well concrete stair rising six flights, with a tubular metal handrail. The top of the stairs leads to two airlock chambers separated from the shaft by double sets of steel blast doors, intended to provide a barrier against potential contamination in the event of nuclear attack, thereby maintaining a safe environment within CGWHQ.

All above ground structures are excluded from the scheduling. The scheduled area includes a 1m margin on all sides as well as above and below.

Source: Historic England

Reasons for Scheduling

Slope Shaft (Emergency Exit) A in the CGWHQ, below MoD Corsham is designated as a Scheduled Monument for the following principal reasons:
* Period: it is testament to the importance of the subterranean aircraft factory in World War II, and secondarily to the perceived threat of nuclear strike that Britain faced during the Cold War;
* Rarity: this fortified access route is a bespoke construction specific to the CGWHQ;
* Survival: it retains the sub-structure of the escalator, the operational plant and the blast-proof doors;
* Group Value: the CGWHQ site is an unparalleled example of our national Cold War defence heritage, and represents the systematic use of expansive underground areas by industry and the military during the C20.

Source: Historic England

Sources

Books and journals
Hennessy, P, The Secret State, (2010)
McCamley, N J, Secret Underground Cities, (2000)
McCamley, N J, Cold War Secret Nuclear Bunkers, (2002)
McCamley, N J, Second World War Secret Bunkers, (2010)
Fox, S, 'Subterranea' in Top Secret - Acid, (2010)

Source: Historic England