Hms Nelson; Building Number 58

This is a late 18th-century office building, originally part of the Royal Naval ordnance storage and distribution system at Portsmouth, and later associated with HMS Vernon. It is also known as The Customs House. The building is constructed of patterned red brick with grey brick headers in Flemish bond, with Portland stone dressings, and has a Welsh slate hipped roof. It is of a late Georgian style and has a T-shaped plan, with offices arranged off a central axial corridor.

The two-story facade is 15 bays wide. It has an ashlar plinth and plat band, alongside a stepped, dentilled eaves cornice below a coped parapet. There are 6/6-pane sash windows with stone sills. A central three-bay section is broken forward into a pediment, which contains a double six-panel door with a formerly boarded-up overlight, approached by a flight of three stone steps with iron railings. A stone panel in the pediment previously held a gilded and painted Royal coat of arms, surrounded by a rope design.

The rear features a projecting central stair bay, with later infill sections on either side. A round-arched entrance and window are located above the stairwell. There are two segmental-arched ground-floor openings with 9/9-pane sashes. The main range of the building has round-arched recesses on the first floor, originally containing round windows (oculi), of which only two remain. The right return has oculi with glazing bars; the right-hand one has been replaced with a window. The left return has a central window on each floor, flanked by oculi; the ground-floor left-hand oculus has been converted into a window.

The interior retains many original features including six-panel doors with butt-beaded outer panels, chair rails, and a partly rebuilt central Imperial stair in the rear projection, with round-arched doorways leading off. Double doors provide access to the principal first-floor room.

The building controlled the storage and issue of armaments and ordnance stores for naval ships and represents a significant survivor from the original Gun Wharf Yard. It is similar in design to the 1770s office at Priddy's Hard and forms part of the historic dockyard complex at Portsmouth.