A daughter church of the seventh-century Christian mission established in Llandinam, the present church dates from the fifteenth century and all four walls still incorporate medieval stonework, including squared red sandstone from the remains of the Roman fort at Caersws. This is despite extensive renovation in 1863 by R. K. Peston which added the spinneret, porch, and Decorated-style tracery. The current church is built of rubble stone with limestone dressings and is an example of a Welsh single-chamber church, comprising an undifferentiated nave and chancel, a southern porch, a northern vestry, and a western spinneret supported on a waterboarded timber-framed tower projecting from the southern end of the church roof. The southern side of the church is lit by three-light windows with cusped heads under depressed arches and has a priest door to the west of the porch over which is a quatrefoil roundel. The north side has similar two-light windows. The window on the eastern end is a three-light, fifteenth-century panelled window with grotesque headstops for a now missing hood moulding. Inside the church is an exceptional carved fifteenth-century roodscreen and loft, the best-preserved of thirty known to have existed in the county. The loft is reached by steps made of fourteen solid oak blocks. The pulpit is early-seventeenth-century with carved panels. The font is a plain nineteenth-century copy of the original, fifteenth-century octagonal font which is set nearby. In a northern window a fifteenth-century stained-class image of the patron saint, St. Gwynnog, has been reassembled. The saint is represented in the robes and mitre of an abbot, with a crozier in his left hand and his right raised in blessing. Beneath him is the inscription `Sce Gwinog?.

(Sources: Thomas, `Montgomeryshire Screens and Roodlofts?, Montgomeryshire Collections, XXXII (1902), 12-16; Inventory of the Ancient Monuments in Wales and Monmouthshire: Montgomery (RCAHMW: 1911) p. 140; Scourfield and Haslam, The Buildings of Wales: Powys (London: 2013), pp. 186-87; Cadw site report)
A.N. Coward, RCAHMW, 17.04.2018