26 Clarendon Street, Londonderry, County Londonderry, BT48 7ET

26 Clarendon Street is a mid-terrace, two-bay, three-storey with attic, red brick Georgian-style townhouse built in 1863. It stands within the Clarendon Street Conservation Area in Londonderry, on the north side of the street at the junction with Princes Street. Its original character and much of its period detailing survive intact, and it shares group value with Nos. 6–24 and 28–48 Clarendon Street, a continuous run of similar early to mid-Victorian townhouses constructed over an eight-year period lining the north side of the street.

The building is rectangular on plan with a projecting return to the rear, and sits over a rendered plinth. The principal (south) elevation faces onto Clarendon Street behind a low cement-rendered wall, with a concrete ramp rising to door level. The roof is pitched natural slate with black clay ridge tiles, continuing over the rear return. A slender red brick chimney stack rises from the west side, centred on the ridge and topped with terracotta pots. Cast iron half-round guttering on rise-and-fall brackets serves the front elevation; uPVC rainwater goods are fitted to the rear.

The front elevation is laid in Flemish bond brickwork. All windows are six-over-six timber sliding sash, set in square-headed openings within painted cement-rendered reveals with painted sills. The entrance doorway has a three-centred arched opening with a moulded surround, a moulded cornice supported by Doric columns on either side, a four-panelled painted timber door, and an Adam-style fanlight above. At ground floor level, two diminished windows sit to the left of the door. The first and second floor windows — two per floor — are not aligned with the ground floor openings.

The west (gable) elevation is blank, cement rendered, and topped by a single large red brick chimney stack. A high cement-rendered boundary wall extends to the rear of the property, with a timber-sheeted door to the rear yard accessed from Princes Street. The east side of the building is abutted by the adjoining No. 24 Clarendon Street.

The north (rear) elevation is red brick, three storeys high, with an attic dormer to the right and a three-storey pitched-roof return built at half-landing height to the left — the left half of this return belongs to No. 24. The right bay of the main block has a single replacement uPVC casement window at ground floor, with six-over-six timber sliding sash windows to the first and second floors, surmounted by a replacement uPVC casement within a pitched-roof attic dormer. The rear return to the left is surmounted by a single replacement uPVC casement window, and its north face is abutted by a single-storey extension with a six-over-six timber sliding sash window to the first and second floors. The west face of the rear elevation has a door at ground floor to the far left, a single diminutive two-over-two timber sliding sash window at first floor, and a single diminutive casement window at second floor. The east face is abutted by the return of No. 24. An additional single-storey extension with hipped roof, cement-rendered walls, fibre cement slate roof, replacement casement windows, and uPVC rainwater goods abuts the rear of the main block.

To the north end of the site stands a single-storey brick outbuilding with a pitched fibre cement slate roof, accessible from a laneway to the north.

The development of Clarendon Street sits within a broader story of urban growth in Londonderry during the mid-19th century. The area, recorded on the first edition Ordnance Survey map of 1830 as rural hinterland within the townland of Edenballymore, lay beyond the established limits of the city at that time — development had reached no further than Waterloo Place, Abbey Street, and William Street. The only significant structures north of the walls in the early 19th century were isolated institutional buildings: the Londonderry Infirmary, the Lunatic Asylum, and Foyle College. The sole domestic building predating the Victorian development in the area is Foyle Cottage, a Regency house of around 1815. Robert Simpson's Annals of Derry (1847) recorded that the entire district later covered by Great James Street, William Street, and Little James Street had originally been meadow ground without a house.

From the late Georgian period into the Victorian era, uniform rows of neat three-storey townhouses transformed this area into a new and affluent quarter favoured by the city's merchant and professional classes. The geometric street layout of Clarendon Street, Great James Street, and Queen Street was characteristic of Georgian town planning and represented the most ambitious planning exercise in Londonderry since the construction of the walled city between 1613 and 1619. A plan of Londonderry dated 1847 — drawn up at least a decade before the street was completed — shows Clarendon Street under its original name of Ponsonby Street, so named in honour of the Right Reverend Richard Ponsonby (1772–1853), Bishop of Derry and Raphoe. By the 1850s it had been renamed Clarendon Street in honour of George Villiers (1800–1870), Fourth Earl of Clarendon and Lord Lieutenant of Ireland between 1847 and 1852. The second edition Ordnance Survey map confirms the new name was in use by at least 1853.

Although the 1847 plan showed Clarendon Street extending from the quay to Francis Street, only the lower section between Strand Road and Queen Street had been laid out by 1853. Development progressed slowly through the 1850s: in 1851 Skipton and Miller had advertised building ground on Clarendon Street, Queen Street, and Patrick Street to let in perpetuity, and Griffith's Valuation of 1856 recorded only nine dwellings along the entire length of the street. Further leases for building ground on the northern side were advertised in 1856.

No. 26 was one of the final buildings to be erected along the north terrace. Built in 1863 alongside Nos. 6–10 and 22–24, it completed the continuous terrace of eleven houses running between Queen Street and Princes Street. The house was constructed for John Allen, a wine merchant and property owner with business premises in Linenhall Street, and was originally valued at £28. Its first recorded occupant in 1863 was a Mr Allen Black. By 1901 the house was occupied by a Ms Jane B. Jackson; the census of that year classified it as a first-class dwelling comprising ten main rooms. The Allen family retained ownership until at least 1931, after which, by 1935, the entire row of Nos. 6–26 had been purchased by a Ms Jennie Steen. The First General Revaluation of Property in Northern Ireland (1935) increased the building's assessed value to £40. The Second Revaluation (1956–72) recorded it still in use as a private dwelling, valued at £35.

In 1978 the Department of the Environment designated Clarendon Street and the surrounding streets a Conservation Area, described as an area of special architectural or historic interest whose character it is desirable to preserve or enhance. No. 26 was subsequently listed in 1979. Records note that the brickwork to the front elevation was repointed in 1983, and in 1990 the former dwelling was converted to office use — a change that has detracted somewhat from the building's original character. By 2013, the architectural historian Calley described Nos. 6–48 Clarendon Street as a "delightfully long red brick terrace of the mid-19th century," noting that the buildings are nearly all the same — three-and-a-half storeys, two bays, with most ground floors "rather inelegantly squeezing in a doorway with two reduced scale window bays," and with "depressed arched recessed timber-framed doorways hav[ing] simple segmented fanlights and thin Doric columns supporting entablatures." Few of the mid-Victorian townhouses along Clarendon Street are now occupied as residential dwellings; the majority were converted into offices for dentists, solicitors, and accountancy firms in the late 20th century.