Former RAF Alconbury: Alert Facility Building (Building Number 103)

This is a security police headquarters building constructed in 1977 for the United States Air Force. Designed by JE Gray, structural engineer to the Public Services Agency, and built by George Wimpey Limited, the building is rectangular and aligned roughly east to west, with two separate penthouses at the west end housing blast valves.

The building is of reinforced concrete with red facing bricks to the first floor, except for the blast valve penthouses. A grassed earthen berm surrounds the ground floor on all sides, cut through at the south-west corner by revetment walls for a service road. A flat-roofed entrance passage projects from the north-east corner.

The first-floor southern elevation is primarily of painted reinforced concrete, comprising the blast valve penthouses. This section features four rectangular openings, two with original louvered ventilation grilles and two with replacements. The remaining portion of the elevation is of stretcher bond red brick and is largely blind, except for an off-centre left doorway concealed behind a blast wall. The rear elevation is also blind, featuring an emergency exit shaft enclosed by railings to the off-centre left and a recessed blast valve penthouse with three rectangular openings – two with original louvered ventilation grilles and one with a replacement grille.

The ground-floor entrance passageway leads to a stairwell containing an open-string concrete staircase with square-section metal balusters and a moulded handrail. A wall painting depicting the seal of the United States Department of the Air Force is on the stairwell wall. The first-floor retains its original room layout, including a gun mount room, weapons equipment room, ammunitions store, and toilets, all with original steel doors. Between the weapons equipment room and gun mount room are three steel-meshed service hatches with steel security doors and spy holes. The guard mount contains a pair of wooden clearing barrels – safety devices for capturing discharged rounds – and the ammunition store contains an ammunition cupboard along with a wall painting depicting the head of an eagle. The ground floor is believed to retain its original layout, with spaces for a weapons security officer, Flight Chief, and clean and dirty plant rooms.

Beneath the ground floor are three underground chambers: one containing a steel oil tank, another a steel effluent tank, and a third concrete chamber for storing cold water, located beneath the clean plant room.