His father was Lord of Hanslope[2] and hereditary Chamberlain of the Exchequer, a title that went back to another William Mauduit who held that office for King Henry I of England.
According to 15th-century chronicler John Rous, the walls along the northeastern side of Warwick Castle were destroyed, so "that it should be no strength to the king".
[3] William and his wife were then taken as prisoners to Kenilworth Castle and were held there until the payment of a ransom of nineteen hundred marks was given.
[5] When he died, his estates passed to his sister Isabel who had married William de Beauchamp, Lord of Elmley.
Isabel died shortly after her brother, and the title passed to her son William de Beauchamp, 9th Earl of Warwick.