This compact defensive structure, measuring roughly 4.88 metres east to west and 4.4 metres north to south, features a pointed archway that once held a two-leaf gate. Above, a slot in the roof housed a portcullis, providing an additional layer of security. Visitors passing through would have entered a barrel-vaulted passage, just over 4 metres long and 2.1 metres wide, flanked by doorways; a now-destroyed entrance on the north side and a smaller round-headed doorway on the west, constructed with undressed stones.

The western doorway leads to a spiral staircase tucked into the southwest corner, which climbs to the first floor chamber. This room, measuring approximately 4.44 by 2.82 metres internally, was strategically positioned to control the portcullis mechanism below. Windows pierce three of its walls, providing light and defensive viewpoints, whilst the eastern wall is shared with the church’s south aisle. The spiral stairs originally continued upward to a second floor, though this level required corbels projecting from the north and south walls for support, suggesting a timber floor construction.

The second floor likely served as living quarters or a guardroom, with single windows in three walls matching the arrangement below. Most intriguingly, evidence suggests a doorway in the eastern wall at this level, which would have provided direct access to the wall-walk along the church’s south aisle. This architectural detail reveals how the religious and defensive elements of the priory were physically integrated, allowing defenders to move between the gatehouse and church fortifications without descending to ground level.