St Cattwg's Church has twelfth century origins, but its nave and chancel were rebuilt between1284 and1307. In the fourteenth century the south aisle was altered to create the Raglan chapel, and the west tower was added. The nave, chancel, and chapel were re-roofed in the fifteenth century. Further restoration was undertaken beween 1887 and 1888. The church, which retains many of its medieval features, is constructed from coursed limestone rubble with a double pile roof and a perpendicular porch. The chancel, nave, and south aisle all have fifteenth cradle roofs. The transitional Norman chancel arch is supported on large impost blocks with Romanesque dogtooth design. There are remains of the fifteenth century rood screen, which separates the Raglan chapel from the south aisle. The Norman font has crude decoration.

The church contains a fragment pillar cross shaft, thought to be 11th-12th C., which, along with the extensive churchyard, has been taken to indicate the presence of an early Medieval monastry (see Nprn275855).

A remarkable series of wallpaintings were discovered and conserved in 2010 -11. These include Death and the Gallant, St George, Deadly Sins and Works of Mercy, along with other traces, including painted and gilded canopied reredos in nave. There is an Apostles Creed in English in the south aisle and other text fragments.

Wallpainting conservation in progress 2010/11; samples from timbers removed during roof restoration taken for tree-ring dating 2011. Summary of available archaeological and architectural information provided by Amelia Pannett and Rick Turner, 'St Cadoc's Church, Llancarfan: Historical Research and Building Recording (Archaeology Wales Report 1004, 2011). 

Sources include:
Undated noted by A.J. Parkinson. 2004.03.12/RCAHMW/SLE
Cadw listed buildings database
Os495card; ST07SE28

Amelia Pannett and Rick Turner, 'St Cadoc's Church, Llancarfan: Historical Research and Building Recording (Archaeology Wales Report 1004, 2011). 

Richard Suggett, Painted Temples: Wallpaintings and Rood-screens in Welsh Churches, 1200–1800, (RCAHMW 2021), pp. 106, 107–9, 134, 139, 147–78, 186, 189.

RCAHMW 2021