Bethania Welsh Presbyterian Church

The interior has a complex plan whereby the main chapel is linked by side arches to the vestry, end gallery and organ chamber to the R of the pulpit. The main chapel has one of J H Morgan's typical densely timbered roofs, 5 bays, the main part open, ceiled at upper collar level, with sloping sides and vertical panels below. Trusses have tie-beam (on corbels), main collar, with pilaster posts between and further posts above to the apex collar. A longitudinal beam runs down each side from the end gallery, carrying the side vertical panels. A flat ceiling is between this and the walls.

The end gallery projects with curved angles, pilaster divisions between panels, boarding under the moulded rail, under shallow shouldered arches. Thickly moulded top rail. More ornate fluted applied pilasters with panelled tops are between every second panel and against the walls at the ends. Panelled underside with moulded beams. Fluted rebated pilasters beneath each side and 2 similar posts.

Two big arches open to the vestry at the end of the L side. High panelling under leaded big mullioned arched lights. Pews are in 3 blocks with boarded backs and flat caps to the bench ends. Inward-facing pews are on each side of the pulpit. The set fawr surrounds a table with a classical design of cornice over square piers. The pulpit behind has 3 steps up on each side, with concave swept rail, square pulpit front of 3 open bays with paired turned balusters between, a moulded rail and bookrest. The tall back to the platform is boarded at dado level, has vertical tall panels above, centre recessed under a segmental arch with narrow panels under flat cornice, and sides have with similar top panel and cornice at lower level. The back wall is slightly recessed to echo the gallery recess at the opposite end. Three small lights are set high. A marble memorial to Rev William Prytherch (d 1888) by D R Williams, Llanelli, is to the L, organ in arched recess on right side wall.

The vestry has open trusses, tie-beam with posts up to collar.

Chapel of roughcast with ashlar dressings and slate roofs and coped shouldered gables. Its unusual plan is derived from house design, and comprises the chapel range parallel to road, with centre ridge lantern, a lower vestry wing projecting to the L, a 2-storey porch bay, containing a stair to the gallery, projecting to the R and flat-roofed lobby between with coped parapet. The main chapel narrows for the gallery at the L end, the re-entrant angle obscured by the porch bay. Windows are generally flush ashlar with rusticated sides, with some chamfering to the main windows. Leaded glazing. The chapel side wall has 2 narrow windows of 2 lights over a single pane, above the lobby, which has a door to the L in a plain ashlar frame, and 2 small narrow lights. The porch bay has a first-floor small 2-light unmoulded window over the ground floor broad ashlar doorway with deep chamfered jambs, moulded segmental arch dying into piers and curved hoodmould stepped over the centre, which is dated 1911. The roof is carried down over an outshut to the R, with one small single light to front, and 3 stepped lights in the side wall. The vestry has one unmoulded side window and a big end-gable 3-light window, segmental arched with stepped hood, as on the porch. The window has stone mullions, a single transom, and chamfering to the outer frame only.

The chapel end wall has a large 5-light mullioned and transomed window similar to the vestry window but with recessed intermediate mullions in the top-lights. Three ground floor plain single lights are below. The side wall has a windowless, recessed L end, then the main part has 3 long windows, 2-light above a transom, single-light below. A lean-to organ-chamber with continuous roof is to the extreme R. The ridge lantern has a copper base, battered louvered sides and a copper pyramid cap with finial.