Somewhere in the south wall of the structure, a fieldworker examining the site in 1983 noticed what appeared to be a doorway, centrally placed and blocked up with rubble and burnt stone. The burnt material was the telling detail. The working theory was that this sealed opening was not a doorway at all, but the back wall of a kiln, a small industrial furnace, built up against the exterior face of the castle wall and making use of it as a ready-made structural support. It is classified officially as a "possible kiln", which is the archaeological record's polite way of saying: probably, but we cannot be certain.