Circular and moated.The motte is about 5 metres above surrounding land.
see http://homepage.mac.com/philipdavis/English%20sites/1146.html
For once I disagree with the learned gent,Philip Davis.I think it's more probable that it was an adulterine castle,from The Anarchy,ie erected without the King's Permission,and reduced afterwards,as was the custom,re-used later as a mill mound.