Mount Ross, 20 Ballygarvigan Road, Ballygarvigan, Portaferry, Co Down, BT22 1JT

Mount Ross is a large, formal, two and a half storey gentleman's residence built in 1747, possibly by Turner Camac, at a cost of £1,500. Despite 20th-century alterations, the house retains significant architectural interest.

The house stands on a rise just off Ballygarvigan Road, approximately 3 miles northeast of Portaferry, surrounded by a large random rubble wall with a raised garden. The front elevation faces southeast and is symmetrical. The facade is finished in lined render with chamfered quoins and painted. A chamfered plinth runs along the base.

The ground floor features a central gabled and glazed porch covering the original doorway, with flights of steps to either side leading to timber glazed doors. The original doorway within the porch has a timber panelled door with plain fanlight, set within a moulded architrave with entablature. Two small basement windows, now boarded, sit at ground level on either side of the porch. Two sash windows with Georgian panes flank the porch on the ground floor. The first floor has five evenly spaced windows, similar in style but slightly shorter. A small central flush gable sits above the eaves with a semi-circular eyebrow window.

The southwest gable has a small two-pane attic window to the right, with top-hung upper opener. The northeast gable contains a similar window to its right and has a small single-storey lean-to extension attached to the gable, featuring a small fixed light window to the front southeast elevation of the main house, a multi-pane steel window to the northeast elevation, and a plain sheeted timber door to the rear.

A large two-storey flat-roofed return was added to the rear in 1909, now featuring timber windows with horizontal and vertical astragals, made to resemble sashes but with various top-hung, bottom and upper openers. The northwest face of the return has two evenly spaced windows to the first floor, one to the left of the ground floor, and a door to the right. The northeast face has a ground-floor window slightly right of centre and a first-floor window right of centre. Flanking the return on the rear facade of the main house are sash windows (6 over 6), with one at each floor level. At the base of the wall is a sheeted door giving access to the basement.

The rear facade is finished in lined render but unpainted. A long line of modern flat-roofed dormers runs along the rear of the main house roof, with timber window frames. The main roof is gabled and covered with Bangor blue slates. Two recent brown brick chimney stacks with uniform pots serve the main house, and a tall rendered chimney stack rises from the return roof. A large shallow metal water tank for rainwater collection covers almost the entire roof of the return. A small moulded heart-shaped plaque inscribed "Oct. 1909" adorns the middle of the rear of the return.

PVC gutters and downspouts are fitted throughout, with an oversized gutter to the front elevation. The site includes a large yard with extensive single and two-storey outbuildings to the rear; a large two-storey outbuilding to the northwest side of the yard is roofless.

In 1829, the house came into the possession of the Lyttle family, a local farming family, through an uncle who had purchased the property in 1803. An 1838 valuation return notes that "the house and offices are too large for the present occupier, having been occupied formerly by a man of large income", with valuers advising that rates be reduced in accordance with owner Francis Lyttle's modest means. The rear return was constructed in 1909, and the glazed entrance porch was probably added at the same time. The large flat-roofed rear dormer was built circa 1970.

The listing extends to the house, gates, gate piers and walling.