The main architectural elements of the church of St. Cadoc indicates that it was built in the fifteenth century, but its call and some details (piscina, arcade in the presbytery) suggest that it could have been much earlier, maybe already at the beginning of the thirteenth century, as the local parish was recorded in documents for the first time in 1254. Probably the original church from that period underwent a major reconstruction in the fourteenth or fifteenth century, during which it was enlarged with a chancel and a tower. In the second half of the nineteenth century, it underwent a Victorian renovation carried out by John Prichard.
At the end of the Middle Ages, the church consisted of an oblong, rectangular nave, also a rectangular but narrower and shorter chancel on the east side, a tower on the west side and a porch at the southern entrance portal to the nave. On the south side, the nave received late Gothic double and triple windows crowned with cinquefoils in a rectangular frames. The chancel has two two-light windows in four-sided jambs in the northern and southern walls, and pointed windows with three-light traceries on the eastern and southern sides.
The tower is four-sided, divided by a cornice and topped with a battlement. On the north-eastern side it has a turret with a staircase. The room with the bell was opened on each side with a large pointed-arched window divided by shaft into two openings, each of which was topped with a trefoil.
Inside, the presbytery was separated from the nave by a pointed arcade, in the northern wall of which there was a hagioscope (squint opening). It was probably used by choir priests to observe the priest at the main altar, as on the sides of the arcade there could be altars for praying for the souls of the dead. On the opposite side, a piscina was placed in the southern wall of the nave, and another was placed in the southern wall of the chancel. Until the 16th century, the space intended for ordinary believers was separated by therood screen from the presbytery. It was a wooden, richly decorated partition with an upper balcony to which led stairs in the thickened part of the northern wall.
The internal façades of the church in the Middle Ages were covered with colorful figural polychromes with a large proportion of red and yellow colors. The stained glass in the windows also added splendor, judging by the found relics, showing not only simple patterns, but also figural scenes.
The church is one of the best-preserved late medieval churches in Glamorgan, which have only undergone careful Victorian restoration. Thanks to this, the original roof truss, tracery and window jambs of the church have survived. Inside, on the southern wall of the nave, a valuable 15th-century fresco has been preserved, depicting St. George fighting a dragon and a piscina in the presbytery. Particularly valuable is the beam from the rood screen from the end of the 15th century, with intricate decorations of floral motifs.
Salter M., The old parish churches of Gwent, Glamorgan & Gower, Wolverhampton 2002.
Website britishlistedbuildings.co.uk, Church of St Cadoc A Grade I Listed Building in Grosmont, Monmouthshire.