Wellington House, 11 The Square, Hillsborough, County Down, BT26 6AG

Wellington House is an end-of-terrace, three-storey over basement redbrick townhouse built around 1780, forming part of a terrace of four on the northern side of The Square in Hillsborough, County Down. It faces south onto The Square, abutting the Military and Stable Yard of Hillsborough Castle. The house is slightly wider than the other houses in the terrace and is rectangular on plan, with a single-storey extension to the rear and an L-plan two-storey rubble stone former coach house.

The roof is pitched natural slate with black clay ridge tiles. Brick chimneystacks rise to either end, capped with clay pots; the east stack is shared with the adjoining house at No. 12. Cast-iron guttering on iron brackets sits on a projecting brick eaves course, with a cast-iron downpipe. The external walls are of handmade redbrick laid in Flemish bond with cement pointing, above a lead-lined plinth course over a pebble-dash rendered basement wall. The square-headed window openings have rubbed brick flat arches, painted masonry sills, and 20th-century timber sash windows with angled horns.

The front elevation is three bays wide across three storeys over basement, but reads as four windows wide, with evidence of a former door opening in the left bay. The doorcase is off-centre, round-headed, and painted, comprising moulded pilasters rising from plinth blocks to impost blocks, with an archivolt and keystone. There is a replacement timber panelled door, a timber transom, and a replacement fanlight. The door opens onto a granite step leading to a concrete-paved platform that extends to the left bay, reached by three granite steps. Steps and the basement area to the east are enclosed by a wrought-iron railing on a low rendered wall. The west side elevation is abutted by No. 10, known as the Guards' House.

The rear north elevation is redbrick, three windows wide, with a staggered arrangement of square-headed brick-arched window openings, rendered reveals, and 6/6 or 3/3 timber sash windows. At basement level there is a redbrick extension, three windows wide, with a hipped natural slate roof. The east side elevation is abutted by No. 12.

The setting is notable. The rear landscaped garden is enclosed to the west by the tall rubblestone rear elevation of the Military and Stable Yard of Hillsborough Castle, and to the north by the original rubble stone, gable-ended, two-storey coach house with a natural slate roof and brick-lined window openings. The coach house interior retains some cobbled flooring. Abutting the north end of the coach house is a stone and brick mews building, partly rebuilt around 2000, fronting onto a rear access lane with two carriage arch openings and a first-floor loading bay opening onto a cobbled front area. This rear lane gives access to the entire terrace and to Hillsborough Castle. There is a small railed basement area to the front.

The interior retains many original features dating from the 18th and 19th centuries, reflecting the elevated social status of those who lived at this prestigious address overlooking the gates to Hillsborough Castle.

The house was named Wellington House by Lord Arthur Hill in the 19th century. Its origins are documented in a letter of February 1779 from Lord Downshire's agent, John Gardner, who wrote: "we are now clearing the ground for the four houses to be built in the square." The house is shown as a plain rectangle on an estate map of 1788, and as the residence of Sir George Atkinson on a map of around 1800. Atkinson had served as surgeon to the Downshire regiment from 1797, a position he found uncongenial. He subsequently settled in Hillsborough, and correspondence with Lord Downshire survives in which he describes the aftermath of Admiral Duncan's defeat of the Dutch fleet — one of the most significant events in British naval history. The local population apparently suspected Atkinson of trying to dampen the celebrations. He reported: "…to cut the matter short in the evening a mob, headed and led on by Mr John Dickson, attacked my house (while I was from home) and threw in a volley of stones into the parlour where my mother and Mrs Greenfield were sitting at tea. Luckily no other mischief was done than breaking a number of windows."

The Archaeological Survey of County Down notes that the house originally had a vehicle passage at ground floor level, which has since been blocked and converted to living accommodation, and that the doorway has been rebuilt.

By the time of the Townland Valuation of 1828–40, the house was listed as the residence of George Crichard, with a house, offices, and yard valued at £14. By Griffith's Valuation of 1856–64, William Sands was in occupation, leasing from the Marquess of Downshire. The property was then valued at £23, later raised to £24, and dimensions are recorded for a house and return, basement, scullery, five outbuildings, and a shed. William Sands was the architect responsible for the remodelling of Hillsborough House in the late 1830s and 1840s. He worked with his relative James Sands, extending the south front to the east and adding a giant Ionic portico. He also supervised the erection of the monument to the third Marquess in 1848. Sands died in 1881, describing himself in his will as a retired architect. By 1887 the house had passed to Edwin Sandes, perhaps a son. By 1903 it was the residence of William John Walker, and by 1905 of George Allen — listed in the 1910 Street Directory as secretary of the public reading room and accountant and keeper of muniments for the Downshire Estate office. The house has been described as the grace-and-favour residence of Lord Downshire's secretary and his family. It was sold by the Downshires in the 1970s. In 1976 the house was listed, and in 1979 the rear extension was replaced. In 2005 an outbuilding to the rear was converted into an apartment.

The listing covers the house, its steps, railings, coach house, and walling. Together with the other houses in the terrace, Wellington House makes an important contribution to the setting of both the former Market House and Hillsborough Castle.