The history of Caversham Park goes back to at least Norman times, when Walter Giffard, a distant relative of William the Conqueror, was given the estate after the 1066 conquest. The estate, then Caversham Manor, was a fortified manor house or castle, probably nearer the Thames than the present house. The estate was registered in the Domesday Book, in an entry describing a property of 9.7 square kilometres (2,400 acres) worth £20. The estate passed to William Marshall, Earl of Pembroke and Protector of the Realm, in the late 12th century. Marshall, who in his final years acted as de facto regent under the reign of a young Henry III, died in Caversham Park in 1219.