St Decuman's is the parish church of Watchet, along the coast of north Somerset, and it has a peaceful, tree-lined location on the southwest edge of town, just off the B3191, on a minor ridge above the valley of the Washford River. The church is notable for its great age, with several components from the early 13th century, including the walls and roof of the chancel, floor tiles in the choir, and wooden carvings at the base of the barrel-vaulted roof; the rest of the structure is 15th century, or later. Also of interest are a number of elaborate monuments to members of the Wyndham family, wealthy local landowners.
The original church at Watchet is thought to have been situated half a mile north right beside the coast, near Daw's Castle (of which only earthworks remain) and its adjacent Saxon settlement, and was probably abandoned due to coastal erosion, sometime in the 12th century. Decuman (died about 706) was a Welsh monk who sailed to Somerset and settled in Watchet, living life as a hermit, accompanied only by a cow. The rebuilding of the initial church was partly financed by the Wyndham family, who had resided in Watchet since the early 15th century, the first couple being Sir John Wyndham (ca1495-1573) and wife Elizabeth Sydenham.
St Decuman's Church is reached by a short side road which runs alongside the extensive graveyard, both the recent easterly addition and the original area next to the building. There is parking space for several vehicles at the entrance. The church has a simple layout, with a tall, square-based tower at the west end, its outer corners each reinforced by a pair of study buttresses, linking to the four bay-nave and the chancel, to the east. The nave is bordered on each side by aisles, both of which were extended eastwards, partly along the chancel, by addition of chapels. Entry is through the 15th century south porch. The nave and chancel are equal in width and height, giving the impression of a single space, and share the same roof in the form of a barrel (or waggon) vault, supported by ancient wooden ribs and bosses. The lower end of each rib meets a wider transverse plate adorned with carved angels. The nave and the chancel are divided only by a thin, full height stone arch and by an elegant wooden rood screen, the lower part of which dates to the 15th century.
The church organ is set against the west wall of the nave, above a doorway to the tower. Nearby is an octagonal stone font, 15th century, situated below one of the aisle windows, most of which contain modern glass, though at least one, a narrow lancet in the north wall of the chancel, is from the 13th century. The east end of the north aisle holds the Wyndham Chapel, containing various monuments to the family, most elaborate being the alabaster effigies of Henry (died 1613) and brother George (died 1624), great grandchildren of St John. Another Wyndham monument is centrally located in the chancel floor, below the altar, this is for Edmund Wyndham of Kinsford, and consists of several brass elements set in a rectangular stone slab. The stone, and two others, abut the floor between the choir stalls, formed of 13th century floor tiles, probably produced by the monks of nearby Cleeve Abbey since they are identical to some surviving at that place.