Building 124 (Mixing House), Rnad Bull Point

Gunpowder Mixing House, later store, now office, built in 1804. Single-storey rubble construction with corrugated sheet roof.

The building has a single-depth plan and a single-storey elevation with a five-window range. The wider central section features a large central doorway to the rear, fitted with segmental relieving arch to double half-glazed doors, with segmental-arched 3/3-pane sashes on either side. The south elevation contains three small central windows with 20th-century glazing and taller 6/6-pane sashes to the narrower ends, all with segmental-arched heads. Small doorways are positioned at either end, that to the east having a brick arch.

This building was constructed as part of the St Budeaux Royal Powder Mills, which was incorporated from the 1850s into the new Bull Point naval ordnance yard serving Devonport Dockyard, completed in 1854. The complex provided storage for 40,000 barrels of powder and integrated facilities including a floating magazine for unloading powder and the St Budeaux laboratory for checking and processing before transport to the Bull Point magazines. Bull Point, situated just north of the Royal Navy's new Steam Yard at Keyham, was the last great project of the Board of Ordnance before its abolition in 1856. Unlike other yards, Bull Point was planned from the outset with a dedicated set of ashlar buildings with rock-faced dressings, fronting an avenue to the south of the magazines. These form a stylistically coherent and remarkable example of integrated factory planning of the period, comprising the finest ensemble in any Ordnance Yard.

This is the only surviving building from the earlier St Budeaux powder works. The mixing house was where raw gunpowder materials were combined before being incorporated in the mill. Earth traverses reinforced with masonry minimised explosion effects, with the boiler supplying steam to the stoves positioned between two semicircular traverses. By 1866 it was converted to a dining room, and in the early 20th century served as a store. The footings of other structures remain clearly visible on the site.