Kempton Park Pumping Station (Including Triple Expansion House and Two Attached Chimneys)

Kempton Park Pumping Station, including its triple expansion house and two attached chimneys, was built in 1929 to a design by Henry Stilgoe, Chief Engineer for the Metropolitan Water Board, and constructed by William Moss. The building is constructed of red brick and Portland stone ashlar, with a slate hipped roof. It has a rectangular plan, including a parallel rear boiler house and a rear octagonal chimney linked to a chimney of Kempton Park I (built around 1903). The architectural style is Baroque Revival.

The pumping station is single-storey with an attic and basement, featuring a 7-window front. The symmetrical front has a banded rusticated plinth, cornice, and coped parapet. Massive clasping buttresses incorporate paired pilasters, terminating in a raised section above the cornice with round panels. An ashlar porch with steps leads to panelled doors, flanked by Diocletian windows, a cornice, and a matching front window. Brick screen walls contain tall round-arched windows with flat lintels and metal-framed windows with margin bars. The attic windows are rectangular with diagonal glazing bars, separated by stone strips, and feature a central panel inscribed 'METROPOLITAN WATER BOARD'. A projecting raised terrace has banded ashlar walls and a ridge lantern. The returns feature central doorways and three narrow windows, along with two attic windows. A lower rear engine house connects to a parallel boiler house range to the rear.

The interior is tiled, with green pilasters supporting the gantry crane. It houses a pair of original and complete Worthington Simpson triple expansion engines, named the Sir William Prescott and the Lady Bessie. Brass lamps illuminate the central open basement area, crafted from components of an 1812 Boulton and Watt parallel motion beam engine. Further features include an entrance lobby, stairs to a panelled office above, and a walkway supported by steel modillion brackets.

The station is accompanied by a unique pair of octagonal brick stacks attached to the rear, with square bases and cornices. The 1929 chimney is linked to the c.1903 chimney of the Lilleshall engine house by a rusticated ashlar arch.

Historically, the pumping station represents the pinnacle of steam-powered water pumping engine houses, and contained the two most powerful pumping engines in Europe, which delivered water to the Primary Filter house (built in 1929) and service reservoirs. It is listed for its architectural merit and group value alongside the 1904-5 Kempton Park Lilleshall engine house, which once formed the highest concentration of steam engine power in Europe. The site is also designated as a scheduled ancient monument.