1-3 The Diamond, Portstewart, Co. Londonderry, BT55 7EA

An altered two-and-a-half-storey former house, now a hotel, with large modern extension. Built in 1875 and converted to a hotel in 2006, the building is located on the east side of The Diamond in Portstewart town centre.

The building was originally a traditional two-storey rendered townhouse. It is rectangular on plan, abutted to its north gable by a large modern extension and to its rear by a modern linking block. The pitched natural slate roof is fitted with blue and black angled ridge tiles and painted render chimneys. Plastic rainwater goods sit on projecting eaves.

The walling is rubblestone with lime pointing and red-brick flat arches. Windows are replacement 6/6 timber sash with horns, flat brick arches and projecting cement sills. Four gabled dormers have been inserted into the roof. The principal elevation faces west and contains five openings at each floor, though those at first-floor level are irregularly spaced. The ground floor has been substantially altered with a large plate glass window inserted to the left of centre. Modern panelled timber doors to the far left and right are surmounted by flat brick heads. The north gable has a window to the right of centre at attic level and is almost entirely obscured by the modern glass curved extension, which extends to the northeast. The south gable is abutted by the adjoining building and its upper section is blank.

Extensive alterations have compromised the original character. These include a raised roofline, the four dormer insertions, replacement chimneystacks, replacement fenestration throughout, enlarged openings at ground floor, and exposed rubblestone walling to the facade.

The building occupies a prominent position on The Diamond, facing west towards an important junction on the approach to Portstewart town centre. The area is characterised by mainly commercial units housed in two-storey terraces on the southern edge of the town. The hotel is set back from the road with a tarmacadamed public parking area to the front. To the north side of The Diamond stands Agherton Parish Church.

Historically, buildings stood on this site from at least 1830, though valuation records from that period describe four low-value structures, each valued between £1 and £2 10 shillings, which were likely single-storey vernacular buildings. The terrace was remodelled in its present form as seven dwelling houses between 1875 and 1882, reflecting Portstewart's growth as a successful bathing resort. The row is without architectural pretension and likely retained fabric from its simpler predecessors.

The present houses at 1–3 The Diamond were originally a single dwelling built by William Martin, a grocer, in 1875. Martin had occupied the previous house on the site from 1866, and gradually expanded his holding by adding outbuildings in 1868, appropriating a garden from the neighbouring house in 1872, and finally rebuilding the house entirely in 1875. This substantially increased the valuation from £1 15 shillings to £17. By 1888 the valuation had been reduced to £15, possibly as a result of an appeal.

In 1900 the property passed to Henry Dixon, who operated a clothiers shop from the 16-room premises. The 1901 census records Dixon as a 32-year-old merchant tailor living with his wife, three young children, and a domestic servant aged 18. In 1905 the premises passed to Charles Upson, a grocer with three children; the property fell vacant by 1912. John Richardson was a subsequent occupant, recorded as present in the 1930s.

Valuation records from the 1930s indicate that the two-storey house contained a single-storey shop measuring 15 by 20 feet, with a single-storey brick scullery and bathroom to the rear and a separate WC. A separate outbuilding and store comprised two sections, with the single-storey section having a corrugated iron roof. The accommodation included two reception rooms, six bedrooms, a scullery, pantry, bathroom and WC. Samuel Scott took over the house in 1939 and appears to have divided the building into two separate dwellings, a division recorded from 1953 onwards.

The building was listed in 1977. In the 1970s, architectural historian Girvan commented that The Diamond was "a pleasant enclosure, away from the sea-front...and dominated by the Parish Church."

In 2006 permission was granted for the conversion of 1–5 The Diamond and the replacement of 2–4 Lever Road to the rear with a 17-bed boutique hotel featuring lounge bars, restaurant and conference facilities, designed by Kevin Cartin Architects Ltd. The development ultimately also incorporated number 7 as a snug bar. As part of the conversion, the roof line was raised and dormer windows fitted. The front elevation has been largely retained, though little original fabric remains to the rear.

Despite extensive alterations that detract from its original character, the building remains representative of late-nineteenth-century domestic architecture. Its prominent position on the approach to the town, combined with its group value alongside other listed buildings in the terrace, gives it special historic interest.