21 Clarendon St., Londonderry

21 Clarendon Street is a mid-Victorian mid-terrace townhouse of two bays and three storeys with an attic, built in 1874 as part of a group with Nos. 17 and 19 Clarendon Street. It forms part of a terrace of twelve predominantly brick-faced townhouses lining the south side of Clarendon Street, with the wider group extending across Nos. 5–19 and 23–73 (excluding No. 53), built over a twenty-one year period. Nos. 17, 19 and 21 were the last properties completed in this terrace and are distinctive in character from their neighbours. The building is rectangular on plan with a projecting rear return. It has been converted to office use and internally linked with No. 23, resulting in some modernisation of the interior, though its original character and much of its historic detailing survives. It sits within the Clarendon Street Conservation Area, and its well-preserved setting adds to its interest. The building is listed in its extent as a house.

The principal elevation faces north and sits behind a low rendered boundary wall surmounted by replacement metal railings. The ground floor of this front elevation is painted render, while the upper floors are red brick laid in Flemish bond, with a rendered band at eaves level. A single red brick chimney stack sits to the west side, centred on the ridge, and carries nine octagonal clay pots.

All windows are one-over-one timber sliding sash unless otherwise described. Ground floor openings are square-headed; upper floor windows are segmental-arched. To the left of the front elevation is a square-headed entrance doorway surmounted by a projecting moulded cornice supported by a pair of pilasters painted in a contrasting colour, with console brackets featuring acanthus leaf detail to either side. The doorway is fitted with paired half-glazed two-panelled painted timber doors with a single-pane square-headed overlight above. To the right of the door is a single tripartite timber sliding sash window — comprising three one-over-one sashes — surmounted by a hood mould supported by four console brackets with acanthus leaf detail, also painted in a contrasting colour. The first and second floors each have two windows, though these are not aligned with the ground floor openings. The first floor windows have a continuous sill course and painted moulded surrounds with keystone detail. The second floor windows have painted moulded surrounds. At attic level there is a pitched slated roof dormer containing a painted casement window with top-hung opening lights.

The east and west elevations are abutted by the adjoining buildings at Nos. 19 and 23 Clarendon Street respectively. The south rear elevation is cement rendered and three storeys with an attic. A pitched roof four-storey rear return projects to the right, also cement rendered. The fenestration to the rear is irregular and includes a mix of casement windows and one-over-one and two-over-two timber sliding sash windows. Ground floor windows are obscured by metal grilles. The rear elevation was not fully visible at the time of survey. At ground floor level there are two one-over-one timber sliding sash windows; at first and second floor left there is a single one-over-one timber sliding sash window; and at attic level there is a pitched roof dormer to the left containing a casement window.

The fenestration of the south gable of the rear return is also irregular. At ground floor level there is a single window opening to the left, abutted to the right by a single-storey pitched roof building with a blank south gable and east face. The west face of this outbuilding has a window opening to the right and a door opening to the left. The rear return itself has a single central two-over-two timber sliding sash window to the first floor; a single small one-over-one timber sliding sash window to the second floor, with its right reveal aligned with that of the window below; and a top-hung casement window to the third floor right. The east face of the rear return is abutted by the return of No. 19 Clarendon Street; the west face was not visible at the time of survey.

Roof coverings are natural slate, rainwater goods are cast iron, the walling is render and brick, and windows are timber throughout.

Clarendon Street was laid out in the early Victorian period, with the first dwellings constructed from around 1853. The street followed a geometric layout characteristic of Georgian town planning — the most ambitious such project in Londonderry since the construction of the walled city between 1613 and 1619. The area now occupied by Clarendon Street and the surrounding streets had previously been rural hinterland; as late as 1830 the city's built fabric extended no further than Waterloo Place, Abbey Street and William Street, and the Clarendon Street area, lying within the townland of Edenballymore, was open country. The only significant early building nearby was Foyle Cottage (a Regency house of around 1815), along with isolated institutional buildings such as the Londonderry Infirmary, the Lunatic Asylum and Foyle College. By 1847, when Robert Simpson compiled his Annals of Derry, the area that would become Great James Street, William Street and the surrounding lanes had within living memory been described as meadow ground without a house.

The street was originally named Ponsonby Street, after the Right Reverend Richard Ponsonby (1772–1853), Bishop of Derry and Raphoe. It had been renamed Clarendon Street by at least 1853, in honour of George Villiers, Fourth Earl of Clarendon (1800–1870), who served as Lord Lieutenant of Ireland between 1847 and 1852. A plan of Londonderry dated 1847 already showed the proposed layout of the street — then still called Ponsonby Street — extending from the quay up to Francis Street, though only the lower section between the Strand Road and Queen Street had actually been laid out by 1853. Development was slow throughout the 1850s; Griffith's Valuation of 1856 recorded only nine dwellings along the entire length of the street. In 1851 and again in 1856, building ground on Clarendon Street and neighbouring streets was advertised to let in perpetuity.

Nos. 17, 19 and 21 were built in 1874, approximately two decades after the initial development of the street, and as a result they display a distinctly Victorian character that sets them apart from the Georgian-style terraces built earlier — though those too were constructed during the Victorian period. The three houses were built for Forrest Reid, a local solicitor with business offices on Richmond Street. No. 21 was originally valued at £32 in 1874. In 1901 the house was occupied by Alexander Craig, a mechanical engineer whose firm, A. & G. Craig, operated from Queen's Quay; the 1901 census building return described it as a second-class dwelling of eight rooms with a stable and coach house as rear outbuildings. Ownership remained with the Reid family until at least 1931, when Nos. 19 and 21 were purchased by a Mr. Joseph A. L. Johnston. In 1935, under the First General Revaluation of Northern Ireland, the house was increased in value to £49. By the time of the Second General Revaluation (1956–72), the property was owned by a Dr. F. W. Craig, who converted the ground and first floors into a private medical surgery while retaining the upper floors as domestic apartments. By the cancellation of the revaluation in 1972 the total value of the property stood at £98. In 1978 the Department of the Environment designated Clarendon Street and the surrounding streets a Conservation Area. No. 21 was subsequently listed in 1979. The roof was reslated in natural slate in 1987, and the windows were replaced following damage caused by a bomb explosion in 1992. The building continues to be used as office premises.