The small village of Marcross lies approximately four kilometres to the west of Llantwit Major in the Vale of Glamorgan. The parish church, dedicated to the Holy Trinity, stands near the southern end of the village, about one kilometre from the Bristol Channel. The church is of simple plan with a saddleback W tower, an aisleless nave with a S porch and a lower, square-ended chancel. Where the fabric is exposed, it is evident that the local Lias limestone was the principal building material. Sutton Stone — a freestone available from nearby quarries — has been identified in the quoins of the chancel and several of the window mouldings (Evans (1988)).

The church’s Norman origins are signalled by the Romanesque chancel arch, the S doorway and, perhaps, the large tub font. The plain, round-headed tower arch may be of a similar date but, like the tower itself, it is devoid of features that can be confidently dated.

Although a fine incised cross slab now in the chancel floor commemorates an unknown early 13thc priest, there is little evidence for further works to the church until the later Middle Ages. The N-W nave window has been dated to the late 13th or early 14thc, and the tomb recess in the N nave wall may be of a similar date (Evans (1988)). A low stone screen rebated for a central door was inserted beneath the chancel arch, perhaps in the 14thc.

The rood screen stair was accessed from the chancel and the upper doorway facing the nave retains portions of the wooden door frame, with a four-centred head surmounted by a slight ogee curve, probably of 15thc date. The chancel windows were renewed in the 15thc. The tall, southern window was provided with a transom to create a low-side, or ‘leper’s’, window.

A cross base and a portion of the shaft, probably dating from the late 15thc, survive in the churchyard. They now support a later sundial.

The Norman lordship of Marcross was probably established in the early part of the 12thc. Although the Liber Niger of 1166 makes no mention of the holder of the fee, in a charter of 1173–83 Bishop Nicholas of Llandaff confirmed to the abbey of Tewkesbury ‘two parts of the tithes of the demesne of Marcross (dominii de Marois)’ alongside other tithes granted from fees founded before 1135. In the late 12thc, Marcross was held from the lord of Glamorgan for the service of one knight (Crouch (1988), 30; RCAHMW (2000), 449).

Philip, lord of Marcross, attended upon King Henry II when the latter visited Cardiff in 1172 and was the deputy sheriff of Glamorgan a decade later. Around 1180, Philip granted 14 acres of land in Marcross to the Cistercian abbey of Neath. This grant was later increased to 36 acres by Philip or his successor, another Philip. The abbey established a grange at Marcross, probably marked by the earthworks in the fields to the north-east of the village (RCAHMW (1982), 258–60).

Around 1262, the knight’s fee of Marcross was divided between two heiresses, who conveyed moieties to the Bere and Anne (Vann) families. The latter was responsible for raising Marcross Castle — more properly a strong house — in the later 13th or early 14thc; fragmentary remains have been incorporated into farm buildings standing some 275m to the N-E of the church (RCAHMW (2000), 448–53).

Although no 12thc documentary references to the church of Marcross have been discovered, clergy who presumably are serving it — Richard, priest of Marcross and Philip, priest of Marcross — appear in witness lists from the late 12th or early 13th centuries (Clark (1910), 160–61, 384–85; Foster (1950), 201, 204–06; Crouch (1988), 52–53).

Marcross was located in the rural deanery of Groneath and Robert, rector of Marcross, acted as one of the jurors for the deanery in the Valuation of Norwich in 1254. Marcross was valued at 5 marks at that time (Lunt (1926), 323–24). In the ecclesiastical valuation of 1291 ordered by Pope Nicholas IV, it was valued at 15 marks (£10) (Denton and Taylor (1998), 149).

Marcross remained a rectory throughout the rest of the Middle Ages and was valued at £10 12s 6d in the Valor Ecclesiasticus of 1535 (Green (1906–07), 137; Orrin (1988), 265).

The church was restored sympathetically by Kempson and Fowler in 1893. The roofs were renewed, the S porch was rebuilt, a new E window and other windows were inserted, new furnishings were installed and the font was moved to its current position (Orrin (1988), 267).

Thurlby notes that the south doorway is very ambitious for such a small parish church and suggests that it was produced by a sculptor recruited from Llandaff. Like Butler ((1971), 385), Thurlby notes parallels between the foliage carving on the capitals at Marcross and the capitals of the presbytery arch at Llandaff Cathedral. He also remarks that the lack of abaci on the capitals and the roll moulding in the arch are closely similar to the south presbytery windows at Llandaff. In considering the striking grotesque label stops, Thurlby observes that a stop at Gloucester shows a similar treatment of the eyes and suggests comparisons with corbels at Kilpeck ((2006), 175–76).

In his analysis of the chancel arch, Thurlby notes a similar raised ribbon chamfer with a volute at the top on the chancel arch at St Clears in Carmarthenshire and draws parallels with the spear-like terminations on the crossing piers at St Dogmaels in Pembrokeshire ((2006), 176).

While Newman (1995, 420) would date Marcross to the late 12thc, Thurlby, citing the parallels noted above, prefers a date in the second quarter of the 12thc ((2006), 177).

Williams notes that the pillar stoup or piscina is made of Sutton stone ((1893), 343).