St Mary's Cottage, Duns Castle Estate

St Mary's Cottage is an earlier 19th-century cottage style house, situated within the Duns Castle Estate. The building is irregularly planned, broadly L-shaped, and constructed of whinstone with droved ashlar dressings, with rubble and whinstone with sandstone dressings to the rear. The base course is prominent, with flush sandstone quoins and chamfered arrises to the window surrounds.

The southwest elevation has five bays; the central three bays project forward and have blank whinstone panels on either side. The eaves are lowered to a single-story level over these central bays. A Doric colonnaded recess is centrally located, featuring a timber lintel and columns. A flush-panelled door with a diamond-paned fanlight sits behind the colonnade. Timber mullion and transom windows with canopies are present in the flanking bays.

The northwest elevation shows three bays relating to the main house and the rear of a projecting northeast range, with the bays to the outer left set back. A bay to the right is advanced. A timber mullioned and transomed window is centrally located at ground level, with a relieving arch above. A piended dormer breaks the eaves on the first floor. To the left, a mullioned window at ground level has a relieving arch, while a mullioned window sits above it on the first floor. A timber transomed and mullioned window at ground level is located in the right-hand bay, above which is a mullioned window on the first floor.

The southeast elevation is four bays wide. A single-story bay is located penultimate from the left, with a later, blocked square panel present. A canted window is situated at ground level in a gabled bay to the far left, with a mullioned window above it on the first floor. The bays to the inner and outer right are of a later period, built from rubble and whinstone rather than the original whinstone. Each bay features timber mullioned windows at both ground and first floor levels.

The northeast return elevation displays a boarded door with a 3-pane rectangular fanlight, alongside a window in the bay to the right.

The southeast elevation of the northeast-projecting range features four bays in an irregular arrangement. A timber-boarded porch provides access via the return southwest elevation, with a bargeboard on the northeast gable and a window immediately to its left. A window is located to the outer left, with an off-line bipartite window breaking the eaves and featuring a piended roof. A boarded door is found in the bay to the inner right, alongside a window to its immediate right; a window breaks the eaves and is piend-roofed above. An additional window breaks the eaves and has a piend-roofed appearance in the bay to the outer right, with a buttress alongside it. A later garage, slightly set back, has boarded sliding doors.

The windows throughout vary, with diamond-paned timber casement windows facing southwest, northwest, and southeast (the 1st floor windows of the southeast elevation have leaded lights). Eight-pane timber sash and case windows are found on the northeast return and the southeast elevation of the northeast projecting range. The roof is complex, slated with jerkin-head roofs to the outer bays of the northwest elevation and in the bay to the left of the southeast elevation. An inverted U-shaped dormer with a diamond-paned casement window is located centrally on the southwest elevation. A modern single-pane rooflight is on the northeast projecting range, and a 2-pane rooflight is centrally placed on the garage.

The interior retains original features. These include shutters, cornices, a black marble chimneypiece, and a picture rail in the drawing room. A cast-iron banister with a timber rail and dado is a feature of the staircase.

A later ashlar sundial, with a circular base and shaft and upper plate, sits to the southwest of the house.