P test-stands and support structures, former Royal Ordnance Establishment, Westcott

P Test-Stands and Support Structures, Former Royal Ordnance Establishment, Westcott

The P site comprises two test stands, P1 and P2, located close to the northern edge of the test area, with P1 positioned to the north-east and P2 to the south-west. They are constructed from reinforced concrete, sheet metal, steel girders, earth bunds, and brick.

P1 remains in its late 1940s form as an open-roofed firing bay shored by sheet piles with steel girder edging. It was backfilled in the mid 1990s, which has preserved its original form. The firing bay is protected by a large earth traverse incorporating discreet fuel bays to keep oxidant and fuel separate, and a semi-detached observation bay with periscope viewing capability. A channel collects spent fuel while another directs the test flume. A ramp survives for accessing the top of the test stand, via which the test vehicle or missile would have been lifted into the stand by crane. The control room, Building 301, lies south-east of the stand. It is a sunken rectangular reinforced concrete building with a flat roof, protected by concrete retaining walls and the earth traverse. This design, with greater separation between the firing bay and the observation and control areas, was implemented in direct response to the fatal explosion at D stand in November 1947.

P2 was originally identical in form to P1, an open-roofed firing bay protected by a substantial earth traverse, but has undergone three distinct phases of modification visible externally. It was heightened in the late 1950s to accommodate testing of the rocket motor for Blue Streak. The upper stage and roof, clad in corrugated sheet, date from its drop-test incarnation of the 1970s and 1980s for Chevaline. Having remained in use until more recently and avoided the infilling of P1, P2 presents a more immediately legible structure, with the ramp directing the test flume visible and channels allowing run-off to nearby settling ponds. The loading ramp accessing the top of the stand also survives. Internally are partial floors and connecting ladders. The semi-detached and semi-buried control room, Building 303, is positioned to the north-west of the stand and shares the same form as Building 301. It retains some machinery, though this dates from its drop-test incarnation rather than the 1950s. Holes for the original observation periscopes survive. A drawing of P2 shows the main test chamber, the deflector bucket below it to deflect the flume on firing, and ancillary equipment for high pressure gas and fuel storage and transfer. Photographs in the site archive chart various test firings of P2 from the mid to late 1950s, documenting the modified superstructure.

Building 304 stands to the north-west of the stands. It is a bi-partite flat-roofed structure: the north-east portion is red brick (formerly site security, not of special interest) and the south-west portion is reinforced concrete (former instrument store). The building was not internally inspected.