Capel Seion including Railings

Chapel in coursed rock-faced squared sandstone with tooled dressings, red sandstone window tracery and slate roofs. The chapel presents an imposing street front composed of a broad gable with a broad 6-light window set back behind a flat-roofed embattled porch framed by two squat towers with slate pyramid eaves roofs. The towers vary in size, detail, and placement. High plinths support the structure, and the coped main gable has slightly humped copings to the shoulders.

The broad segmental arch over the 6-light window features cusped heads to the main lights and 12 tiny cusped lights in the arch, with a heavy roll-moulding. The porch below is subtly asymmetrical, with a parapet containing 3 shallow crenellations on the left and 2 on the right, each side of a shallow curve echoing the cambered head of the doorway below. The door head has a triple moulding that dies into chamfered jambs, and panelled double doors with tiny panes in the heads sit beneath. At each side of the door is a tiny cusped lancet.

The two towers differ in size. The right tower, larger and continuous with the front wall, has a plinth and battered base with deep-recessed cambered-headed 4-light windows above under an overhanging pyramid roof. The windows are red stone with cusped lights and roll-moulded cambered arches. The recess has chamfered sides and the outer tower angles are chamfered, as these were the bases of octagonal angle piers that flanked a low parapet with a needle spirelet behind, now replaced by the pyramid. The left tower is square, with a tiny cusped lancet to the front and another at mid height to the outer side.

Four-bay sides are divided by stepped buttresses with overhanging roofs. Deep recessed cambered-headed traceried windows on each floor feature 2 lights below and 3 lights above, under roll-moulded arches. The windows are red stone with cusped lights. The roof on the left is continued from the pyramid roof of the stair tower, whilst the roof on the right abuts the rear of the tower. To the right of the right side is a lower 2-storey vestry and organ chamber with similar red stone 2-light windows on each floor and a blank gable end with an end-wall chimney.

Attached iron railings front the building and run along the right side, with those at the front being more elaborate and featuring 4 stone cross-gabled piers.

The front porch contains a part-glazed timber screen at each end to the gallery stairs. Two doors lead into the chapel, with glazed top panels. The broad interior has a 4-bay low-pitched sloping ceiling and three trusses with moulded brattished tie-beams and vertical posts with trefoil-cusped arcading between. The ceiling slopes expose double purlins and rafters, plastered between. Arched braces to the tie-beams have pierced spandrels and sit on stone corbels. Windows expose stonework within.

A four-sided gallery curved at the angles stands on 6 plain iron columns made by Macfarlane & Co. of Glasgow. The gallery front has a simple cornice under continuous vertical panels with blind Gothic tracery and a moulded top rail with brass handrail. Steeply raked gallery pews feature shaped bench ends and boarded panelled backs.

A Tudor-arched recess on the fourth side accommodates a large organ by Norman & Beard, dated 1908. Stained pine pews with shaped bench-ends occupy the main floor in 3 blocks, with the front pews of the outer blocks partly canted. A boarded dado runs along the walls. Inward-facing pews sit each side of a 3-sided 'set fawr' with a top brass rail and curved angles. The panelled back features blind Gothic tracery and slopes outwards.

An ornate Gothic pulpit stands in front of the organ gallery. It has 3 panels to the front, one canted on the sides, with inventive blind tracery and gable-capped panelled piers between. A massive cornice is carved with rosettes on the sloping underside, brattished on top, and features a carved bookrest on small carved angels. Massive cross-gabled newels stand at each end, and short steps up each side have heavy Gothic newels with tracery-panel sides and cross-gabled caps. Brass plaques flanking the pulpit commemorate the foundation stone laying on 6 August 1906 and those who died in the First World War. A Tudor-arched doorway to the left leads to the vestry and stairs to the organ.