The Castle's construction at a cost exceeding £10,000 is well documented. But archaeologists and historians seldom agree about dates, and excavations carried out between 1981 and 1985 by the Hampshire County Museum Service illustrate these disagreements. Their most exciting and controversial discovery was of the remains of earlier buildings, cess pits and dressed stone walls, dating from c1100, some two metres below the surface of the existing octagonal keep.
Was it then perhaps a well-fortified hunting lodge that King John departed to sign the Magna Carta at Runnymede in 1215? Was the octagonal keep built after the well-documented siege of 1216 when 13 men defended the castle for 14 days against the might of Louis the Dauphin's French Army?
Although large sums of money had been spent on maintenance and repairs, by the 15th century the castle had ceased to be used as a Royal residence and was described as a ruin in 1603 when it passed from Royal ownership into private hands. It was purchased by Hampshire county Council in 1977 and is a scheduled ancient monument.