Former Engine House and attached boiler houses and coal store, New River Head

Former Engine House and attached boiler houses and coal store, New River Head

This is a Grade II listed building comprising an engine house with attached boiler houses and coal store, built in phases between 1763 and 1849.

The engine house is constructed in brown stock brick with an unusual D-shaped plan. At its core is a two-chamber engine house of 1763, which has lost its north wall. This core is flanked by engine chambers built in 1786 and 1794–5 to the south-west and south-east, with a large curved pump room to the north. A stair tower stands to the west, and conjoined single-storey boiler houses are attached to the south and east. A single-storey coal store range extends to the east. The boiler houses and coal store date from 1845–9 and are built in yellow stock brick. Much of the brickwork has been patched in the 20th century. All external materials include stone cills and coping, with slate roofs and cast-iron window frames installed in the 1840s phase.

The exterior displays plain brick banding between stages. The curved north elevation is particularly distinctive, featuring a tall round-arched window with radial cast-iron glazing bars, an insertion of the 1840s. Upper windows throughout have segmental arches, while lower windows are round-headed. The east elevation has paired windows at different levels. The south elevation is blind except for a blocked window at its centre, inserted in 1786 to light a short-lived staircase; this is the only visible external element of the 1768 engine house. The flanking walls have flat, much rebuilt buttresses and upswept parapets. The west elevation retains brickwork from the 1786 extension, including a pair of offset buttresses, with segmental-arched windows above. The ground-floor entrance was enlarged in the 20th century. The stair tower has a string-course to the parapet and round-arched windows to its upper sections, with a blind ground floor. All elevations are braced with numerous curved iron tie-rods.

The roof is surmounted by an octagonal brick structure which originally supported a metal cylinder, now replaced by a timber louvred cupola. The boiler houses have low hipped roofs; the south-west boiler house has a glazed ridge. Its west elevation features two windows with cambered gauged-brick arches, though the lower section was remodelled in the 20th century with inserted openings. The south elevation is blind with three offset buttresses. The south-east boiler house has late-20th-century louvred openings on the south and a round-arched doorway on the east, with a rebuilt north elevation adjacent to the coal store. The coal store has a hipped roof with a glazed ridge. Originally it had seven arcaded bays, now blocked, three of which retained cast-iron windows. The north elevation has been altered with a large opening with a concrete lintel. A brick lean-to structure along the south elevation was removed in the 1950s.

The interior of the engine house contains an elaborate cast-iron stair of 1848–9, supplied by Henry and Martin De La Garde Grissell of Regent's Canal Ironworks, leading manufacturers of structural ironwork from around 1841. Substantial cast-iron girders from the 1845–9 phase remain in the west engine house, pocketed to carry the ends of floor beams. Cast-iron girders of I-section in the north chamber of Smeaton's original building supported cisterns or condensation tanks to prevent steam loss. The boiler houses and coal store have light wrought-iron roof trusses but retain no other fittings of interest.

The internal compartments largely preserve the configuration of 1794–5, though some walls have been breached in later alterations.