According to Clwyd Powys Archaeological Trust, 'Cemmaes lies in Dyffryn Dyfi, astride the A470 trunk road linking Welshpool with Machynlleth. It is about llkm north-east of the latter. The village has grown up just to the north of where a small stream, Nant Coegen, enters the Dovey, but well above the valley floor. A very steep scarp drops down from the churchyard edge to the river which here passes close to the eastern edge of the valley. The village is compact with all past development occurring south of the church. This has resulted in fairly complete street frontage development as far as Pont y Cemmaes, and the most recent housing has extended the village on to the further side of the stream.
The earliest form of the name, "Kemeys," was recorded in 1254. Though not straightforward, the favoured derivation is from "cam feis" meaning "crooked
fords." The curvilinear churchyard and the British dedication to a local saint favour an early medieval origin for the church (NPRN 400342), but little is known of its subsequent history. As late as 1842, the church was accompanied by less than ten houses, although Lewis recorded that three annual fairs were held here.'
During his travels through Wales in the first half of the nineteenth century, George Borrow described Cemmaes as 'a small town, or large village, with a church at the entrance, and the usual yew-tree in the churchyard.' The village's inn had 'a very comfortable kitchen,' although Mr Borrows was decidedly less complimentary about the inn's customers and the village's residents in general.
The first and second editions of the 25inch OS maps, published in 1889 and 1901 respectively, show that at the turn of the twentieth century Cemmaes had a school, a public house called the Penrhos Arms, St. Tydecho's church (NPRN 400342) and a Welsh Calvinistic Methodist chapel (NPRN 11265). Both places of worship and the public house remain open, although the school closed in September 1971 and pupils moved to the newly-opened Ysgol Glantwymyn, about a mile to the south west.
Sources: Ysgol Glantwymyn website; Clwyd Powys Archaeological Trust report on Montgomeryshire Historic Settlements, published in 1992 by R J Silvester; 'Wild Wales,' by George Borrow, first published in 1862; modern and historic OS maps
M. Ryder, RCAHMW, 19th December 2018