St Ishmael's Church is situated within a rectilinear churchyard adjacent to a stream which empties into Monk Haven some 300m to the south-southwest. The church occupies a possible much larger, curvilinear enclosure defined by field boundaries and routeways and encompassing both sides of the narrow stream valley which leads down to the foreshore. The church is thought to have been mentioned as the bishop house `Lan Ysmael? and as `Lan Yssan in Ros? in documents of the 9th century. Three early medieval carved stones (NPRNs 423612, 423613, 423614) are associated with the site. Ten cist burials containing extended inhumations were recorded during the excavation of a pipe trench in 1976, some 140m to the south-east of the church. Further burials have also reportedly been found to some 140m to the north-east of the church. The church was a parish church during the post-Conquest period, belonging to the Deanery of Rhos. In 1291 it was assessed at £8 and paid an annual pension of 2 shillings to Monkton Priory. It was a possession of the Augustinians at Haverfordwest Priory. At the dissolution the church fell to the Crown, and in 1536 the rectory was leased to Edward Lloid of the king's household. In 1833 the church was in the patronage of the king.

The church is a cruciform building, constructed of Old Red Sandstone rubble. It consists of 4-bayed nave, 2-bayed chancel, 2-bayed north transept with skew passage, single-bayed south transept with skew passage, and south porch. The oolite font with square, scalloped bowl, cylindrical stem and square base, dates from around 1200. It is not possible to closely date much of the church, but the nave may be 13th- or 14th-century in date. The chancel, with plain, two-centred chancel arch, may have been rebuilt in the 14th century. Beneath a window in the south wall is a medieval piscina consisting of a plain, semicircular bowl with drainage. The south porch is thought to be 14th-century in date and a recess in the north-east corner contains a medieval stoup with square, chamfered bowl. The north transept may be later 15th-century, and the south transept appears to have been added as a mortuary chapel, with detail from around 1600. The bellcote may also date to this time. The church was restored in the 1850s, when it was refenestrated, refloored, reroofed and possibly refloored. Openings dating to this restoration are in neo-Gothic style with yellow oolite dressings. The church was again restored in 1884, to the designs of D. Thomas, Haverfordwest, but the reortaion was very light. The oolite pulpit with Purbeck marbel shafts is thought to date to this time, as do the softwood pews and oak vestry screen.

St Ishamel's is said to have been the final retreat of Caradoc of Llancarfan (generally accepted as the author of a Life of Gildas and a Life of St Cadog), who reportedly `spent the latter years of his life in retirement and seclusion? and after his death `was interred with great pomp in the cathedral church of St David's?.

Sources include:
Cambria Archaeology, 2003, Early Medieval Ecclesiastical Sites Project, Pembrokeshire gazetteer
Lewis, 1833, A Topographical History of Wales

N Vousden, 13 November 2018