St Tetta's Church, Llandetty, is set beside the River Usk 12km south-east of Brecon. A simple structure, it has little in the way of features that pre-date the C15th, though conceivably the masonry shell could be C13th. Internally there is a C9th pillar stone and a medieval font, but nothing else of pre-Reformation date.

Wallpaintings in the church include a Hanovarian (1714-1801) Royal Arms on plaster, which still has its complete composition but fragmentary surface colour. The layout lines have been formed by a compass and straight-edge and there has been underpainting to strengthen the colours of bold green, strong red, and tints of ochre. There are variations from the standard pattern because there is no border for Scotland, a reversed lion and incorrect colour harp-strings. The Lunenburgh background is incorrect and there are no hearts. The green colour for blue throughout may be the result of chemical change.

Sources include:
RCAHMW Wallpaintings database. 2004.09.08/RCAHMW/SLE
Richard Suggett, Painted Temples: Wallpaintings and Rood-screens in Welsh Churches, 1200–1800, (RCAHMW 2021).

RCAHMW 2021