Architectural historian Anthony Emery argues that the castle was built in three phases, starting with the central keep, which he believes was intended as a largely unfortified summer residence for the Abbot [REF].
In 1408, the Abbot John Bolton decided that the cost of maintaining the castle was excessive, and attempted to pull down the defences, but was prevented from doing so by Henry IV; this was followed by a period of rebuilding around 1429 [REF].