It was previously thought that treasure was buried under the monument, and digging over the years certainly weakened the foundations and probably contributed to its collapse.
"In the middle of this barton of Trove on the top of a hill is still extant the downfalls of a castle or treble intrenchment called … , in the midst of which is a hole leading to a vault under ground. How far it extends no man now living can tell by reason of the damps or thick vapours that are in it, for as soon as you go an arrow flight in it or less your candles will go out or extinguish of themselves for want of air. For what end or use this vault was made is uncertain though it is probable it was an arsenal or store house for laying up arms ammunition corn and provision for the soldiers of the castle wherein it stands. In the wars between Charles I and his Parliament divers of the royal party pursued in the West by the Parliament troops under Sir Thomas Fairfax were privately conveyed into this vault as far as they could proceed with safety, where Mr Leveale fed and secured them till they found opportunity to make their escapes to the king's friends and party."