Building Number 27, former Groves sergeants' mess (Groves and Henderson Barracks)

This building, known as the former sergeants’ mess, was constructed in 1920 based on designs from the Air Ministry Directorate of Works. It later served as offices.

The structure features red brickwork in stretcher bond for its cavity walls, with some limestone ashlar dressings. The hipped roofs are covered with concrete plain tiles, which replaced the original slate, and are supported by timber trusses.

Situated at the west end of the main parade ground, the building is a near-square, single-storey block with a hipped roof and a small internal service yard. Originally, it included a dining room, writing, reading, and card rooms, a billiard room, and a kitchen with services located at the rear.

On the front (east) elevation, there are small-pane casements, while the returns feature sash windows with glazing bars. The front has a prominent canted bay on either side of the center, with casements framed by bold stone mullions and a transom, arranged in a 1:3:1 light configuration, set flush to the brickwork below and extending up to a parapet with coping above the eaves line. The central entrance consists of a pair of part-glazed panelled doors within a stone pilaster surround, topped by a flat canopy on brackets, and above this is a small tripartite lunette set in a brick arch. Flanking the entrance are tall narrow casements with stone transoms, lintels, and sills. The right return features three sash windows, with the center unit being paired, and an external stack cropped at eaves level near the front. The left return has a small extension with a casement window beneath a swept-down section of the roof, leading to the entry for the service yard. A simple eaves box runs around the entire building.

Inside, original joinery is present, including panelled doors and double doors in the hall set beneath a semi-circular arch.