27 Main Street, Hillsborough, County Down, BT16 6AE

27 Main Street, Hillsborough is an end-of-terrace, two-storey house with attic, built in the early 19th century (between 1803 and 1833) of stone and redbrick, originally rendered. It is a modest townhouse forming part of a terrace of varying house types lining the east side of Main Street, and sits at the elevated upper end of the street where it meets The Square. It has group value with its neighbours at 29 and 31 Main Street, all three having been built at the same time on land owned by a Mr Robinson, and together they contribute to the overall character of Hillsborough.

The house is square on plan, facing east. The roof is pitched natural slate with black clay ridge tiles, two redbrick chimneystacks, a modern dormer to the rear pitch, and cast-iron guttering on iron brackets to a brick eaves course, with a cast-iron downpipe. The walls are snecked uncoursed basalt with squared pink granite quoins and redbrick surrounds to all openings. Window and door openings are camber-headed, formed in redbrick, with replacement concrete sills and replacement timber sash windows. The front elevation is two windows wide, with a replacement tripartite timber sash window to the ground floor and a camber-headed door opening with a replacement timber panelled door and replacement overlight, opening onto two granite steps. The south side elevation is abutted by the adjoining No. 29. The gabled north side elevation is surmounted by a redbrick chimneystack and has rubblestone walling with redbrick to the chimney flue; at attic level there is a pair of square-headed window openings fitted with replacement timber casement windows. To the rear, a full-height lean-to extension added around 2000 is glazed at the upper level with a rubblestone wall at ground level. The north gable fronts onto a shared gravel access lane.

The house was constructed on land owned by Mr Robinson, who is recorded on a 1803 plan of Hillsborough as the occupant of the adjoining Hill House at the corner of Main Street and The Square. The Townland Valuation of the 1830s records the house as occupied by a Ms Rebecca Montgomery and valued at £6. At that time a large square outbuilding was also evident to the rear, though valuation records describe the property simply as a "house and small garden". This outbuilding had disappeared by the time of the fourth edition Ordnance Survey map of 1919–1920.

In 1861, Griffith's Valuation recorded the house as owned by Mr Thomas G. Ingram, who also owned No. 29, and let to Samuel Patterson at £8 10s. rent. It was classified as a 1a-class dwelling measuring six by seven yards over two storeys, valued at £7 (including the rear office). Samuel Patterson occupied the house until 1880, after which the Annual Revisions record at least twelve further occupants between 1880 and 1929. Between 1880 and 1889, Thomas Ingram was replaced as lessor by James Ingram, a weigh-master and shoemaker who lived at No. 29 until his death in 1917. The 1901 census records the house as occupied by Edward O'Hare, a 23-year-old Roman Catholic postman, his wife Agnes (aged 26), and their infant daughter; the house was recorded as a second-class dwelling of only three inhabited rooms. By the 1911 census the house had fallen vacant, though James Ingram remained the recorded landholder. The house was subsequently occupied by a number of residents before Thomas A. Ingram — presumably James Ingram's son — took occupancy in 1929 and remained the final recorded occupant until his death in 1936.

In 1974, the architectural historian C. E. B. Brett described No. 27 as one of "four extremely good stone houses (Nos. 27–33), with some brick trim, some galleting, and most of the Georgian glazing intact." He noted that the house had been used as a shop and illustrated the "pretty former shop-window" visible on the ground floor at that date. The house was listed in 1976. In 1983 major renovations were carried out, including the addition of a rear kitchen extension. In 1999 further alterations were carried out and a glass conservatory was added to the rear. The shop-front was removed — likely as part of the 1999 works — and the front facade was successfully restored to its original design, matching the appearance that No. 29 had maintained throughout. The property lies within a conservation area.