70 John Street, Helensburgh

70 John Street in Helensburgh is a villa built around 1840, with an additional wing added around 1860. This two-storey building has a rectangular plan and features a single-storey wing to the east and a later wing to the west. The exterior is constructed of stugged, squared, and coursed rubble with rendered dressings, and it has a base course and overhanging eaves.

The south elevation, which serves as the entrance, has three symmetrical bays. The central entrance features a doorpiece with stop-chamfered reveals and a timber porch roof supported by two cast iron columns with lotus leaf and volute capitals and urn bases. This porch extends as a corniced balcony above canted windows on either side. The first floor has three tall round-headed windows set in square-headed corniced and pilastered surrounds, with a similar window on the left return.

The east wing is a single-storey, one-bay structure with a window that has a raised margin and a stepped blocking course. The west wing features a base course, lintel course, and cornice.

On the south elevation, there is a slightly advanced tripartite window. The west elevation includes a canted window and another window to the left, with a recessed wing at the far left. The building displays a variety of glazing patterns, including some plate glass and four-pane sash and case windows at the ground floor, as well as glass casements at the first floor, many of which are now broken. The roof is piended with grey slate, and there are corniced end stacks with a full complement of cans.

Inside, the main room in the west wing features elaborate plasterwork, while the first-floor room to the south has a cornice. The windows throughout have splayed and panelled embrasures.