St Mary's Church, Pwllcrochan, is situated within an irregularly-shaped churchyard, which appears to derive from a curvilinear shape. There is a well in the north corner of the churchyard. The church was a parish church during the medieval period. It was granted to Monkton Priory before 1339. In the field to the south of the church, the remains of up to five buildings are represented by earthworks have been noted, along with a routeway running from the south churchyard boundary to join the trackway to the former Lower Henllan Mansion. A triangle or green has been noted towards the middle of the routeway, with a number of routeways and boudaries converging on it. A settlement was recorded at Pwll Crochan during the medieval period and would have been associated with the church. The church is some 300m south of Martin's Haven Iron Age defended enclosre (NPRN 305282), which overlooks the tiny inlet of Martin's Haven and Pwllcrochan Flats.

The church is a Grade 2* listed building, An inscribed stone in the north transept/chapel records the erection of the church in 1342. A square scalloped 12th- or 13th-century font has been removed to St Decuman's Church, Rhoscrowther (NPRN 308950). The chancel was rebuilt in 15th century. An effigy of Rudloph de Benegar is recorded in the south side of the nave. The chancel reportedly had a sedilia, blocked piscine, blocked priest's door and two niches. The church was restored in 1865 and 1897. There is a stencilled nineteenth century dado rail. The church closed in 1982. The site is now situated between Pembroke Power Station and an oil refinery, and in 2003 the church and churchyard were managed by Texaco.

Sources include:
Cadw, Listed Buildings Database
Cambria Archaeology, 2003, Early Medieval Ecclesiastical Sites Project, Pembrokeshire gazetteer
Richard Suggett, Painted Temples: Wallpaintings and Rood-screens in Welsh Churches, 1200–1800, (RCAHMW 2021)

RCAHMW 2022