Thornton, 107 Sinclair Street, Helensburgh

Thornton, located at 107 Sinclair Street in Helensburgh, is a 2-storey, asymmetrical Italianate villa designed by Boucher and Cousland in 1857. The building features stugged, snecked cream sandstone with cream ashlar on the main elevations and polished ashlar dressings. Notable architectural details include base and eaves courses, quoin strips, bracketted overhanging eaves, architraved windows, and moulded chamfered reveals to the ground floor windows.

On the south entrance elevation, there is a recessed bay to the outer right, which includes a pilastered painted porch in a re-entrant angle, an entablature, and a parapet. The doorway features 2-leaf panelled doors and a deep-set half-glazed vestibule door. Above, there are pilastered round-headed windows set in a square-headed panel on the first floor. To the left, an advanced bay has a canted window at the ground level, with a cornice and a decorative stone course featuring linked spirals between the canted window and a bow window above. The bow window has five round-headed lights with column-mullions and polygonal voussoirs, topped with a shallow conical roof and finial. The outer left side has a recessed bay with a corniced window at the ground and a pilastered, bipartite round-arched window above, also set in a square-headed panel, complete with a pilaster-mullion and apron.

The east elevation facing Sinclair Street has two windows at the ground level and two more at the first floor, both with pilasters to the reveals. The north elevation, which faces Millig Street, features a single-storey piended projection off-centre right, with a tall round-headed stair window at the centre and flanking windows. The west side elevation has a window at the centre of the ground floor and a lower 2-storey later block with a piended roof abutting it.

The villa primarily has plate glass sash and case windows, with curved plate glass in the bow window. The roof is covered with grey slate and features corniced ashlar stacks with moulded cans.

Inside, the villa has a corniced hall and a black marble chimneypiece in the dining room. The boundary wall consists of a low rendered wall with semi-circular coping, and rendered piers set back at angles, each topped with semi-circular moulded coping and drum caps.