12 Main Street, Hillsborough, County Down, BT26 6AE

12 Main Street, Hillsborough is a mid-terrace, three-bay, two-storey-over-basement former house with attic, built in the mid-18th century (dated to 1760–1779) and rendered throughout. It was formerly one half of a single, substantial townhouse shared with the neighbouring No. 14 Main Street, and the two properties together retain considerable architectural and historic importance as among the earliest and most substantial buildings on Main Street. The building is currently in use as offices.

The building is rectangular in plan, facing west, with an integral carriage arch to the north bay, a railed basement area, and a lean-to two-storey-over-basement rear accretion. The rear plot was developed around 2001 into a series of modern terraced townhouses known as Church Lane, following renovation and conversion of the main house into offices at that time.

The roof is finished in natural slate, pitched to the south and hipped to the north, with sprocketed eaves and flat-roofed, felt-covered dormers to the north and rear pitches. There is a redbrick chimneystack with clay pots to the north end, cast-iron guttering on iron brackets, and moulded masonry eaves. External walling is painted pebble-dash render with rusticated rendered quoins to the north only; the basement level and rear elevation are finished in smooth render.

Window openings are square-headed with smooth rendered surrounds, painted masonry sills, and 6-over-6 timber sash windows with exposed sash boxes. The front west elevation is four windows wide with an irregular window-to-wall ratio. To the south bay is a round-headed door opening; to the north bay at basement level is an elliptical-headed carriage arch; the two centre bays have a walled and railed basement area. The round-headed door opening has a smooth rendered surround and is fitted with an early 20th-century six-panelled timber door with brass furniture and an original webbed timber fanlight above. The door opens onto three concrete steps flanked to the south by decorative cast-iron railing (belonging to No. 14) and to the north by replacement iron railing on a painted masonry wall enclosing the basement area. Steel grilles protect the basement openings. A modern steel gate closes the carriage arch, which retains exposed structural timbers internally. The rear of the carriage arch opening is built in redbrick.

The north side elevation is abutted by the adjoining No. 10. The south side elevation is abutted by No. 14. The rear elevation is abutted by the lean-to two-storey-over-basement accretion with a natural slate roof, and rises to a flat-roofed dormer that spans almost the entire rear elevation. Rear elevation windows are replacement timber casements; the return has uPVC windows, with the exception of an early 6-over-3 timber sash window to the north cheek of the return.

The irregular facade composition — a consequence of the steep incline of Main Street — is noted as being of particular architectural interest.

The building sits on a steeply inclined site to the east of Main Street, facing west.

Historically, No. 12 first appears on a map of Hillsborough dating from around 1800, where it is shown as a rectangular building midway up the east side of Hill Street, with its rear return and a large oblong outbuilding along the north side of the yard. At that time it formed a single house together with No. 14, occupied by a Mr Bradshaw. The first Ordnance Survey map of 1833 and the contemporary Townland Valuation show little change, though by the 1830s a second outbuilding had appeared at the back of the yard. The Townland Valuation records a Mr Thomas Percy as occupant in the 1830s, with the house valued at £14.

By the second Ordnance Survey edition of 1858, the rear return appears slightly reduced, owing to the demolition of a small outbuilding at its end sometime between 1833 and 1858. Griffith's Valuation of 1861 records a Mr Michael Kelly leasing the house from the Marquis of Downshire at a rent of £19; the house was by then valued at £17 and recorded as a one-B-plus building measuring 12 by 7 yards and two-and-a-half storeys high. The largest outbuilding, measuring 13 by 5 yards, was probably used as a coach house. Kelly held the house until 1864, when it passed to a Mr Frances Heath. Over the following decade the property changed hands several times. In 1870 William Taylor, a sub-inspector of the Royal Irish Constabulary, briefly came into possession but died later that year. In 1878 Robert McCarthy took over and lived there until his death in 1900. The 1901 Census records that his widow, Mary McCarthy (aged 67), continued to live at No. 12 with her son James McCarthy, a local linen manufacturer. The census described No. 12 as a first-class dwelling with ten inhabited rooms and four outbuildings. In 1913 William R. Lilly, a Presbyterian coach builder, occupied the house with his wife Sara and daughter Maggie Alice; the Annual Revisions record his occupation through to 1930.

In 1974, architectural historian C. E. B. Brett noted that the house was in use as a pottery shop and described Nos. 12 and 14 together as "two houses under a single roof ... two-storey with masked basement, coach arch, round-headed doorcases with simple fanlights; very well painted and restored." The building was listed in 1976. In 1989 a conservatory was added to the rear. In 2001 the house was converted into offices, the rear outbuildings (previously used as coach houses, stables, or stores) were converted into separate dwellings, and the yard was renamed Church Lane. At the time of the listing record's compilation in 2010, No. 12 was occupied by a number of businesses as tenants.

The listing covers the office, the front wall, and the railings. The property lies within a conservation area and carries group value with No. 14 Main Street.