St Gastayn's church is situated very near the south edge of Llangorse Lake, set in a polygonal churchyard used as a cemetery. It was built in the period 1848-56 in Gothic Revival Early English style to designs on J.L.Pearson, replacing a medieval church on the same site. This formed part of the extensive redevelopment of the Treberfedd Estate following its purchase in the 1840s by Robert Raikes who had been strongly influenced by the Oxford Movement at University and had become a committed Tractarian, principles strongly reflected in the building which features an almost complete Tractarian interior. Pearson was also responsible for the neighbouring school (NPRN 25958) as well as Treberfedd mansion (16280).
The church is built of coursed rubble with ashlar dressings, steep roofs of stone tiles in diminishing courses, blue ridge tiles, apex crosses, and stepped coping. On plan it comprises nave, gabled south porch, west tower, short and narrower chancel, gabled south-east organ chamber, and north-east vestry. Windows are mostly lancets. The tower is plain and massive, much rebuilt, with plain parapet, north-east staircase tower and big plate-traceried windows. The interior has white walls with exposed ashlar dressings and painted texts, inscriptions and stencilled decoration. The nave is of five bays with arched-brace trusses and two tiers of windbraces, the floor of encaustic tiles patterned in red, yellow and black. Inscriptions are painted below the wallplate and over chancel arch, commandments on each side. There are more texts in the chancel wich has painted rafters and an elaborately decorated east wall. The chancel floor is more decoratively floored, and more so to the sanctuary.
Fittings and furnishings include an octagonal font heavily moulded with quatrefoils, and a pulpit of oak with blind tracery. Stained glass includes works by Clayton & Bell (c.1872), mostly figures set in grisaille.
Sources:
Extracts from Cadw Listing description.
R.Scourfield & R.Haslam, Buildings of Wales: Powys (2013), p.521.

RCAHMW, 9 September 2015

NOTE ON WALLPAINTINGS
Decalogue, texts, stencilling (Vict) Church of 1870 with contemporary decorations: text along nave wall-plate, text around chancel arch, Decalogue on two panels alongside chancel arch; cinquefoil stencilled dado to chancel, text along chancel wall-plate, behind alter, around priest's door; geometrical polychrome decoration on arches and roof-timbers. [AJP'74].
Source: RCAHMW Wallpaintings database.