St Jeffrey & St Oswald's Church is situated within a curvilinear churchyard (extended in the modern period) and raised above its surroundings. The site is thought to be a former iron age defended enclosure and may be surrounded by a larger enclosure, now delineated by surviving boundaries within the village of Jeffreyston (NPRN 268020). A curving cropmark to the south-east of the church may also be associated with an outer enclosure. Boundaries also appear to radiate out from the churchyard enclosure and it has been argued that the church is on the site of an earlier church at the centre of a pre-Conquest settlement with a radial plan. An 8th?9th century cross-carved slab, Jeffreystone 1 (NPRN 422392), was found prior to the 1925 restoration of the church porch, where it had been used as a threshold stone. It is currently set against the east wall of the porch. The church was a parish church during the post-Conquest period, belonging to the Deanery of Pembroke. It may have initially been a possession of the Priory of ST Nicholas, Monkton, but was united with St Issels and transferred to the canons of St Davids Cathedral between 1221 and 1339. The union was dissolved before 1534, but the patronage remained with the Dean and Chapter of St Davids with the tithes leased to a succession of private individuals. The parish had at least one former chapelry.

The church is a Grade II* listed building constructed of local limestone and Old Red sandstone rubble. It consists of 2-bayed chancel, 3-bayed nave, south chapel, 3-bayed north aisle (incorporating a single-bayed north transept and former skew passage), south transept, south porch, 3-storeyed west tower and vestry/organ chamber north of the chancel east bay. The square, scalloped, limestone font bowl with cylindrical stem and base dates to the 12th The nave and chancel are thought to be 13th? 14th century. The transepts (with former skew passages) and chancel each bay may date to the 14th century. The tower, porch and south chapel are thought to be mid-late 15th century. The tower retains its original openings, parapet and vault. The chapel has a medieval 2-centred barrel-vault. The church was restored in 1867-1868, when the north aisle and vestry/organ chamber were added ? the latter converted from a former skew passage. At this time the church was entirely refenestrated, the south door was rebuilt and the current softwood stalls, pews, tower screen and the pulpit were added. The interior was also replastered, reseated, reroofed and refloored. The organ, which occupies most of the chapel, was installed in 1908.

Sources include:
Dyfed Archaeological Trust, 2000, Historic Churches Project, Pembrokeshire gazetteer
Dyfed Archaeological Trust, 2003, Early Medieval Ecclesiastical Sites Project, Pembrokeshire gazetteer

N Vousden, 5 December 2017