The gatehouse, measuring 6.75 metres east to west and 4.3 metres north to south, rises to an impressive five metres at its northwest corner. Built from coursed split stone and rubble bound with gravel and shell mortar, it appears to be a later insertion into the original wall. The main entrance on the north wall showcases medieval defensive architecture at its finest; an arched doorway topped with pitched slabs and approached by three stone steps, though their age remains uncertain. The eastern jamb preserves sockets for three drawbars, those heavy wooden beams that once secured the entrance against unwanted visitors.

The interior reveals a sophisticated defensive layout centred around a wide lobby connecting the north entrance to the south exit. Above, massive pitched slabs roof the northern end of the lobby, with one featuring a curious circular perforation 16 centimetres across, possibly used for observation or defence. The ground floor contains two chambers accessed from the lobby; the eastern chamber, measuring three metres by 1.25 metres, features a defensive loop window set within a splayed embrasure for maximum visibility whilst minimising vulnerability. A similar chamber lies to the west, though smaller at just over a metre square. Both chambers retain their original lintelled roofs, and the doorways show evidence of sophisticated security measures including internal rebates and drawbar sockets.

A stairway built into the western wall leads to the upper storey, lit by two splayed openings that would have provided both light and defensive positions. The upper chamber, measuring 3.1 by 4.8 metres, survives only partially, with the northwest angle and western wall standing nearly to full height. Just 1.8 metres west of the gatehouse, a secondary entrance pierces the defensive wall. Though only its jambs remain today, this smaller passage preserves a drawbar socket and channel, and according to Westropp’s 1912 account, originally stood 1.5 metres high with a flat-headed design. He noted projecting stones above this entrance that likely supported machicolations; those overhanging defensive structures from which defenders could rain down unpleasantries upon attackers below.