Royal Marine Barracks Building 210

Drill Battery, dated 1881–91, with an extension to the north (over basement) added between 1891 and 1911, and a mid-20th-century extension to the south. The building is constructed with a stone basement and timber-framed superstructure clad in corrugated iron, with a gabled corrugated iron roof over timber planking. The rectangular plan has a pointed west end resembling the bow of a ship.

The exterior is 2 storeys in height, with the lower storey functioning as a basement that effectively becomes the ground floor at its western end. Access is provided by a broad flight of steps at the north-west end of the former terrace, by a pair of double sliding doors at the east end, and by a further door giving access to the basement at the west end. The building is lit by windows in the south wall (now partly obscured by the mid-20th-century addition) and by a series of north-facing skylights.

The gun-training deck, originally opening onto a terrace to the north before the 1891–1911 extension, features butt-edged caulked planking flooring. A load-bearing beam secured by tusk-tenons runs along the north side. Roof trusses are of king-post form with iron strapping, bolting and tension rods. Tackle could be looped around these trusses. Beadings and mouldings survive at former side-wall openings, and pulley rings and cleats for mantlets are attached to iron stanchions along the north side of the wall; these stanchions were likely inserted when the extension was built over the terrace. Interior walls are lined in vertical and horizontal planking. An iron shell-hoist shute is visible at the west end of the basement, which is divided into three unequal sections and characterised by a series of parallel stone walls at approximately 5-foot centres. These walls, together with joisting and plates of heavy scantling, were designed to support the gundeck above. Three brick barrel-vaulted storage chambers underlie the terrace.

Historically, this is a unique surviving example of a drill battery in a national context. Three other drill batteries existed at Plymouth, including the Long Room Drill Battery of 1858, which stood to the north-east. Plans in the Public Record Office show a similar plan form with portholes for rifled muzzle loaders in the side walls and pivoted gun mountings to the front. The principal difference is the absence of clerestory lighting in the earlier battery; Building 210 required clerestory lighting for the Royal Navy's new rifled breech loaders and, especially, the operation of their increasingly sophisticated hydraulic pedestal mountings. The floor contains circular cuts which may have housed shutes similar to that surviving at the west end. Gunnery training had been increasing in importance from the 1830s onwards, and this building relates to the period's transition marked by the construction of the first steel-hulled, steam-driven "dreadnoughts".