Number 1 Pumping Station (Building Number 2/201)

This is a dock pumping station, completed in 1878 as part of a scheme designed by Colonel Sir Andrew Clarke (Royal Engineers) and overseen by H Wood, J MacDonell and Charles Colson. The building is constructed of red brick in Flemish bond, with blue brick bands and dressings of gauged red brick and ashlar, all topped by a corrugated sheet roof.

The main engine house has a north elevation of six bays, arranged as two storeys. A two-bay addition is visible at the northwest corner. A lower, full-depth range extends to the left (east) side, incorporating a chimney, although partially obscured by a mid-to-late 20th-century addition. A boiler house range runs along the rear (south side). The north elevation is arranged as a 1:4:1 bay arrangement with broad, banded end pilasters and recessed courses of blue brick. A chamfered ashlar plinth band runs along the base. A segmental-arched pedestrian entrance with a board door is positioned within the left-hand bay. Tall, round-arched windows with metal glazing bars and ashlar arches are featured on the ground floor, with blue brick dentils to the intradoses. A ground floor cornice and a first-floor band frame recessed panels with blue brick edging. Recessed panels on the first floor contain stepped and cogged heads enclosing oculi, each framed by an ashlar architrave. A cornice sits below the parapet. End pilasters on the ground floor have short round-arched windows with voussoirs. Decorative pierced ashlar panels are located between the ground-floor cornice and the first-floor band, as well as segmental-arched windows. The left-hand, lower range has lunettes and a ridge louvre to a hipped, glazed roof. A tall, circular chimney stands nearby, characterized by a square, corniced base and an iron-banded shaft with a roll-moulding at the bottom and a dentilled ashlar cornice at the top. The returns of the main section are similarly styled, with the western return featuring a tall segmental-arched entrance containing a double board door and banded pilaster jambs. The right side of this return has lunettes instead of oculi. The east return (left side) of the lower range has a continuous window featuring panelled wooden pilasters, wooden mullions, and four-pane windows, with a concrete-rendered wall below.

Inside the main engine house, six original panelled cast-iron columns remain, each with dentilled capitals and entablatures. The south elevation, visible within the boiler house, mirrors the exterior style with rusticated pilasters supporting dentilled round arches.

Originally, the engine house housed two inverted vertical triple expansion steam engines driving plunger pumps for draining the docks, alongside air compressors for the caissons and some of the capstans and cranes. Salt water tanks linked to a firefighting main were integrated into the roof. This is an early and architecturally impressive example of a triple expansion engine pumping house, notable for its unusual structural ironwork.