William de Preaux

Often confused with his uncle William the Crusader.

Per David Starr Jordan in his satirical The Inbred Descendants of Charlemagne:

Mary de Redvers de Vernon m. Peter Prouz

William Prouz [brother of Peter?]

Walter Prouz

[William Prouz = Sir William Prouz ]

William Prouz

Alice Prouz m. Sir Roger Moelis

Alice Moelis m. John Wotton

(insert generation here)

Alice Wotton m. Sir John Chichester (and so on)

William Prouz is assumed to be Peter's son because King John made a gift of lands to William on 18 March 1216, which included a promise of the Channel Islands (formerly held by Peter). But - William never got the Islands. He may have been a nephew, or even Peter's favorite brother (the one he went on Crusade with).