The stained glass that now fills the west window of the church was made by the London studio of Heaton, Butler & Bayne, after the church was restored in 1933. It replaced the Renaissance stained glass from the Low Countries, which consisted mainly of New Testament scenes, and was given to the church by Thomas Johnes in about 1805–6.
Following the fire of 1932, fragments of the stained glass were salvaged from among the tiles and molten metal lying on the floor of the church. These pieces of glass were grouped into diamonds and roundels and placed in the smaller two windows at either side of the central chancel window.
The only scene that can be clearly recognised in these smaller windows is the beheading of John the Baptist. These partial scenes as well as various heads and hands executed in paint and silver stain, are mostly suggestive of a sixteenth-century date, made at the Louvain workshops at this time, Curiously, the only date found in the fragments reads 1632, although there is very little evidence of the use of the enamel colour that was characteristic of the seventeenth-century stained glass.
It has recently been discovered that at least some of the Thomas Johnes’ Renaissance stained glass was bought from an abbey church in Antwerp, where he acquired the ‘whole spoil of the Abbey’ in about 1803. Since the rest of this stained glass was destroyed in the fire, these fragments are now all that is left of what was briefly the finest collection of Renaissance stained glass in Wales.