12 St. James' Square

12 St. James' Square is a two-storey building dating from the later 19th century. It has a T-shaped plan, consisting of a main street range and a rear wing. The front facade is rendered and painted, and the roof is covered with Welsh slate. The building has two windows at each level. A slightly off-centre gabled porch has been added. Later 19th-century windows with two panes over two are present, and a three-window bay is canted on the left side at ground floor level. The rear wing is also gabled and rendered and painted.

The interior is complex due to its later use as a school boarding house and master's residence, which has involved the removal of walls, altered floor levels, and divided rooms. Some slight chamfered beams are visible. The roof structure is the most significant original feature, showing evidence of fire damage and multiple periods of construction and alteration. The roof is a principal rafter construction, and the interior has timber-framed partitions with lath-and-plaster walls.