It is, in fact, part of the east gable of a medieval parish church, pressed so close to the Church of Ireland building beside it that the two structures stand within roughly four metres of each other. What remains of the older church has, over time, been absorbed into the landscape of the graveyard itself: part of the surviving north wall now serves as the boundary between the old and new burial grounds, its ecclesiastical origins easy to overlook.

The history of the site, as pieced together by the antiquarian Thomas Westropp in 1904 and 1905, is a layered one. The church appears in records as Garthe or Le Garth from at least 1291, and was dedicated to St Euanganus on the 1st of August 1410. It was connected at various points to Keynsham Abbey in Somerset, and in 1408 Henry IV granted certain customs to the settlement to help wall the town, noting that much of it had been destroyed by, in the words of the patent roll, "Irish foes and English rebels." By 1603 the advowson, meaning the right to appoint clergy to the parish, had passed to Sir Robert Boyle as part of the dissolved estates of Keynsham Abbey. The church fell into disuse around 1810, and an Ordnance Survey account from 1840 noted that part of the east gable still stood in the graveyard, its round-arched window of cut stone still visible. A tower lying about seventeen yards to the south-east, described by Molony in 1905 as comparatively modern in appearance, served as the McCarthy family mausoleum and was said by tradition to have once been used as a vestry. The replacement Church of Ireland building, a Board of First Fruits church with a four-bay nave and a crenellated sandstone tower, was erected in 1820.

The ruined gable stands immediately south of the 1820 church, and the graveyard remains in use. What survives upstanding today is limited to the south wall and part of the east gable; the north wall and west gable have no visible surface remains. The round-arched window opening in the gable, formed of cut stone, is the most legible feature. The well of Saints Peter and Paul was recorded nearby in the Ordnance Survey Letters, though visitors should not expect it to be signposted. The site rewards a slow circuit of the graveyard rather than a glance from the gate.