51 Mountstuart Road, Rothesay, Bute

51 Mountstuart Road is a double villa designed by John Duncan, dated 1877, in the Alexander Thomson style. It is an asymmetrical, two-storey building with five bays, forming part of a symmetrical terrace. The villa is grouped in a 1-3-1 configuration, with single bays recessed to the outer left and right, a full-height gabled bay offset to the right of centre, and an engaged tower offset to the left. The exterior is constructed of yellow sandstone ashlar with polished ashlar dressings, featuring a raised base course and timber bracketed eaves above a ground floor canted window. The roof has a French-pavilion style with stepped eaves and overhanging timber eaves. The windows are square-headed with chamfered reveals, sandstone mullions, and chamfered cills, while the sides and rear are finished in random rubble sandstone.

On the north elevation, there are two-leaf timber panelled doors recessed at ground level in the outer bays, topped with decorative fretwork canopies. A cast-iron brattishing surmounts a three-light canted window offset to the right of centre, with a tripartite window above it at the first floor beneath the apex. There are single windows on both floors offset to the left of centre, with the first-floor window gabled. The full-height engaged octagonal tower in the penultimate bay to the outer left features three-light windows on both floors, a decorative cast-iron bracketed balcony, and cast-iron brattishing above.

The villa predominantly has two-pane timber sash and case glazing and a graded grey slate roof with fish-scale detailing on the tower. The rainwater goods have been replaced, and there is a corniced ridge stack with various circular cans.

The boundary walls consist of a coped random rubble wall along Mount Stuart Road, featuring an oval datestone set in a segmental-arched surround at the centre, inscribed "Royal Terrace 1877," and topped with an anthemion and flanking consoles. The square-plan gatepiers have a raised base course, consoled broken pediments on each facet, armorial panels centered below, and are topped with ball-finials. There are various cast-iron pedestrian entry gates.