That the settlement of its walls is not all of recent date is shown by the heavy fifteenth or sixteenth century buttress built against its north wall, but undoubtedly its dilapidation has seriously increased of late years.
The chapel is a simple oblong in plan, measuring inside the walls 43 feet 6 inches in length by 19 feet 6 inches in width, with side walls 2 feet 8 inches, and east and west walls about 3 feet 2 inches thick.
It is divided on plan into three bays by vaulting inside and by buttresses outside; and divided horizontally in two parts by strings running round the building externally and internally. The height from the floor to the inside string is 6 feet, and from the floor to the crown of the vaulting 21 feet.
Both east and west gables have been taken down, and the whole building is now covered by a low-pitched roof hipped at each end, with a poor modern bell-cote of perhaps about the beginning of the eighteenth century.
At the east end is a triplet of unequal lancets, with well-moulded arches internally and double-shafted jambs, the shafts having carved caps and well-moulded bases, the outer shafts also being banded. The centre light is 8 feet 9 inches high and 1 foot 2 inches wide, the side ones being 7 feet high and 9 inches wide.
The exterior of the west end is extremely effective, a richly moulded doorway under the outer string, which is here raised to a height of 11 feet 10 inches, having above it a very well designed composition of three arches, all well moulded, the outer two being blank and the centre one containing a deeply-recessed vesica window about 5 feet 2 inches high and 2 feet 6 inches in diameter.
The two side walls have each six lancets, each about 8 feet high and 9 inches wide, all with shafted jambs internally having carved caps and moulded bases, but plain splayed arches.
Near the west end of the north wall is a second doorway—now walled up—and in the north-west angle a doorway leading into a stair turret.
The vaulting is quadripartite in the centre and western bays, but sexpartite in the eastern one. The ribs spring from carved and moulded corbels, themselves springing from the string round the building. The vaulting ribs are about 9 inches thick, well moulded with a centre and two side rolls and deep hollows between, the transom ribs having the hollows filled with acutely pointed dog-tooth moulding, the diagonal ribs being without it. The springing of these ribs is about 10 inches above the corbels. There is no ridge rib, but there are well-carved bosses at the intersection of the diagonal ribs, the centre and western ones being all foliage, the eastern one foliage, with the Agnus Dei in the centre.