St Margaret's is a complex, high Victorian parish church first built in 1861-2. It is located on the west side of Dyffryn Road in the fork of its junction with Campbell Terrace.
The church is built of coursed Pennant sandstone with Bath stone dressings, parapet gables with seatings for finials, and slate roofs. Its complicated appearance reflects its complex history. The (ritual) west half survives from J.Prichard and J.P.Seddon's building of 1861-2: nave and south aisle under a continuous roof, richly carved south porch and transeptal gable with bold plate-traceried end window. A matching north aisle and vestry were added by Prichard in 1883-4. In 1895-8 E.M.Bruce Vaughan replaced the chancel with a second, larger south transept, an undersized south-east tower with battlements and a short pyramidal spire, and a straight-ended chancel. Stabilising east buttresses were added in 1986-7.
Internally, the Prichard-Seddon arcades are complicated, the double-chamfered arches oddly related to the square caps of the circular shafts. The chancel has a boarded and ribbed waggon roof. The five-bay tabernacled reredos on the arcaded end wall dates from 1904, designed by Bruce Vaughan.
Elaborate furnishings include pulpit and lectern of 1897-8; stone font of 1905; and organ of 1914, re-modelled in 1952 to designs of Sir Percy Thomas. Stained glass includes works by R.J.Newbery (chancel windows, 1900), James Clarke (north aisle north-east, 1916), Mary Lowndes (north transept, 1917), and A.J. Davies of the Bromsgrove Guild (north aisle, 1930).

Sources:
extracts from Cadw Listing description; J.Newman, Buildings of Wales: Glamorgan (1995), p.451-2.

RCAHMW, 6 January 2015