The plan was originally prepared in September 1922 by Royal Engineers and published by the Ordnance Survey in 1923. It was signed by the preparer and by a Colonel of the Royal Engineers It shows the part of the castle to the north of the church, including the defences, batteries, buildings and land use. The rooms of each building are labelled with their use and the buildings, roads and defences are named. There is a key to the utilities and other measurements (such as room heights).
Copyright Crown copyright