1706, restored by H E Clifford 1904. Hall church with single aisle to NE and office accommodation to SE end. Random rubble walls with ashlar dressings, some droved. Chamfered window arrises.
SW (ENTRANCE) ELEVATION: 6-bay consisting of 4 bays widely spaced, and 2-bay gabled section to outer right. Round-arched entrance to outer left, oval oculus over, raised wallhead above with corbelled parapet. Paired round-arched windows within round-arched opening, glazed at apex to 3 centre bays. 2-bay gabled section with door at ground to left, crowstepped gable above, intersecting with corbelled parapet at corner to right. 2 inscribed stones reading "ERECTED 1706" and "RESTORED 1904".
SE (ST JOHN ST) ELEVATION: 2-storey over basement, 3-bay partially exposed to right. 1st bay, no window at 1st floor, oval oculus to 2nd bay, corbelled parapet above, crowstepped gable behind with Renaissance detail, after Maybole Castle, at apex. 3rd bay, window at 1st floor only, wallhead raised above, with corbelled parapet. Vertically-boarded crypt door with window to left at basement, accessed by stair to small basement area, enclosed by ashlar cope with steel railing.
Leaded glazing to hall and aisle, 12-pane timber sash and case windows elsewhere, 8-pane fixed lights to oculi. Vertically-boarded 2-leaf timber door at main entrance, arched glazed panels in arch head above. Timber entrance door to offices, panelled lower half with 9-pane glazed upper. Grey slate roof and ridge tiles, overhanging timber eaves with exposed rafter ends. Cast-iron gutters and downpipes, hemispherical hoppers with rope moulding decoration. Coped stack with red circular can adjacent to SE gable.
INTERIOR: exposed rubble walls with red sandstone ashlar dressings over wainscoting with vertically-boarded panels and crenellated top. Evidence of infilled arched windows to S wall. Open timber roof to hall of purlins on hammerbeam trusses on stone corbels, triple-apex open timber roofs over aisle, A-frame construction supported on substantial beams. Timber vestibule screen, matching wainscoting, to N end of hall, 2-leaf doors to hall with 4-pane glazed upper panels. Triple arcade to E side of hall with infill of folding panelled timber doors with 5 6-pane arched windows above. 4 bipartite leaded windows in NE wall. Timber floor.
2-storey, 3-bay Masonic Hall to St John Street, attached at W corner.