Set on a hill commanding panoramic views of the coast, Mathry has claims to be one of the oldest settlements in Pembrokeshire.
It was last restored in 1865, but there may well have been a place of worship here since the end of the Roman period.
The south transept has a squinch, an arched covered area where the first hermit or saint might have lived. This might have been the founder’s cell. Another early feature of the church is the Norman font. Surviving medieval fabric includes the vaulted south transept, squint, and west wall with its impressive, massive external buttress.
In the chancel are three 5th to 6th century Christian inscribed stones. One stone was once used as a stile in the wall of the churchyard to the east of the porch. By 1873 it had been set into the churchyard wall and was moved into the chancel in 1905. The Latin script reads 'TUNCCETACE UXOR DAARI HIC IACIT' – 'Tunnccetacem wife of Daarus, lies here'. A primitive linear cross, probably 7th to 9th century has been cut into the lower right hand side of the stone. Two other stones are set into the base of the north chancel arch. These were once used as gateposts on Llandruidion farm, possibly the site of an early Christian settlement. One stone is inscribed with a small cross and the name ‘PAANI’ meaning the memorial stone of Paani. The stone has clearly been split, probably by the farmer who wished to reduce the size of the gatepost. The second pillar stone in the chancel bears the scars of its gatepost existence in the shape of clearly visible holes: six on the face and three on the left side.
A natural spring is located a short distance from the church. This provided the village with water from medieval times until the 1940s and is still used during water shortages. It was rededicated by Bishop Hugh Jones during a pilgrimage in August 1995.