Numbers 20 to 30 and Attached Railings

Numbers 20 to 30 Clarence Square represent a terrace of ten houses, now used as houses and flats, built between 1840 and 1844. The design dates from around 1835-6, attributed to the architect HS Merrett, with numbers 20, 21, and 22 having their upper stages rebuilt between 1980 and 1990. The construction uses stucco over brick, topped with slate roofs. Tall brick and stucco party-wall stacks are finished with cornices.

The terrace presents a symmetrical composition incorporating Tudor-Gothic elements. The central five houses are three stories tall, with the outer two featuring gabled ends. Flanking these are two two-story houses, and a final two-story house with a gable and attic. All houses are built upon basements, with 19 first-floor windows – number 20 has one, while the others have two windows each. Alternate houses feature two-story-on-basement canted bays. The Gothic detailing includes battlements to the bays, hood moulds over windows, and four-centre-arched doorways within engaged porches, which include 'gabled off-set buttresses' surmounted by slender octagonal turrets with blind arcades. An off-centre left entrance, apart from the entrance to number 20 on the left return, is accessed by flights of mostly roll-edged steps leading to mainly four-panelled doors, some of which incorporate lancet panels, with overlights featuring glazing bars – those to numbers 22 and 26 have Gothic glazing bars. A more recent door within off-set 'pilasters' with cornice is found on the left return. Most windows are 6/6 sashes; numbers 21 and 23 have blind boxes. Some basement windows retain 8/8 sashes. Decorative bargeboards adorn the gables, with the exception of number 23. First-floor cornices feature on the canted bays, with first- and second-floor plat bands, a cornice, and a blocking course. Decorative bargeboards are present on number 27. The rear elevation retains many 6/6 sashes.

Interior detailing is limited, with some original joinery noted, including shutters to some windows. Subsidiary features include mainly lancet and stick railings alongside the steps. The forecourt balustrade to number 27 displays a Carron Company double-heart-and-anthemion motif, while number 30 has lancet railings.

The terrace was built as part of the Pittville Estate development for Joseph Pitt between 1825 and 1842, with the overall layout originally designed by John Forbes. HS Merrett produced the designs for the houses on the west side of Clarence Square, succeeding Stokes as Pitt's architect and surveyor in 1835. Clarence Square was laid out in the late 1820s, with building beginning in 1832 and the square named in honour of the Duke of Clarence, who later became William IV in 1830. The terrace is noted for its distinctive style and the strong rhythmic effect created by the canted, full-height bays.