Building 50 (Decontamination Centre)

Decontamination Centre, 1939

This is a reinforced concrete building designed by J.H. Binge of the Air Ministry's Directorate of Works and Buildings (drawing number 6224/37) as part of RAF Bicester's air defence infrastructure. The walls and roof are constructed in reinforced concrete and faced with Flemish bond brickwork above ground level. The roof comprises two stages of reinforced concrete separated by a cavity filled with sand and shingle for blast protection. A protected water tank house sits centrally on the upper roof, containing four 500-gallon tanks.

The building is partly concealed by earth blast protection, with plain walls rising to a flat parapet. The tank housing is a hipped metal-clad addition. The entrance leads through an earth bank.

The interior retains its original layout and plant equipment. The plan comprises an undressing area accessed through an air-lock, a bleaching room, clean clothes store, dressing room, and exit via another air-lock. An air-conditioning plant and boiler room occupy the rear. The building retains steel-shuttered openings for discarding contaminated clothes to the outside. Decontamination took place through a sequence of rooms where personnel could remove contaminated clothing, shower, and change into clean garments.

This building represents an unusually complete surviving example of a specialised structure developed by the Air Ministry in response to the threat of gas attack. Following the Geneva Gas Protocol of 1925, which outlawed the use of gas in war but not its development, the British Government developed methods of protection against chemical weapons. The decontamination centre was designed to treat personnel exposed to gases developed during the First World War: lachrymatory agents, respiratory agents, and blister agents such as mustard gas.

The building's design reflects the particular hazard posed by mustard gas, which has a faint smell and can be absorbed through the skin without detection. Guidance systems including pressure-sealed doors with rubber seals, foot-baths of bleach solution, and guard rails assisted injured or contaminated personnel through the decontamination process. The air-conditioning system supplied filtered air and maintained positive internal pressure to seal the building against external gas contamination. The goal was to remove all contaminated clothing, wash thoroughly, and change into fresh clothing within twenty minutes of exposure to prevent serious injury.

RAF Bicester remains the best-preserved of the bomber bases expanded under Sir Hugh Trenchard's air force development programme from 1923 onwards, retaining layout and structures relating to both pre-1930s military aviation and the development of Britain's strategic bomber force through 1939. The grass flying field survives with its 1939 boundaries largely intact.