Research Notes:
Keats-Rohan's biosketch of "Willelm De Braose" states, [1]
Norman, from from Briouze-Saint-Gervais, Orne, arr. Argentan, cant. Briouze, son of Gunnor, a nun of Sainte-Trinité de Caen in the 1180s. By 1072 at the latest he was one of the five castellans holding the militarily important Sussex Rapes. His holding was known by the late twelfth century as the Rape or Honour of Bramber. He also had holdings in the south-west in Dover, where he had a tenant Robert likely to have been his brother, and in Hampshire. He founded a priory of Saint-Florent de Saumur at Sele in SUssex, some of his grants being the subject of a series of disputes, some of them with his son and heir Philip. He died between 1093 and 1096. His wife's identity is unknown, but she was probably a close relative of the Ralph son of Waldi for whose soul William made a grant to Saint-Florent in the 1080s (CDE, 1112); cf. William Gualdi, who fought the sons of Harold at Exeter with Brien of Brittany in 1069 (Ord. Vit. ii, 224). His issue was an only son Philip, and Agnes, wife of Robert fitz Ansquetil de Harcourt."
Biographical sketches of William de Braose and some of his descendants are available in the online Dictionary of Welsh Biograpy. [2]
[1] K. S. B. Keats-Rohan, Domesday People, A Prosopography of persons occurring in English documents, 1066-1166 (Boydell & Brewer Ltd, 1999), 471, [GoogleBooks].
[2] Dictionary of Welsh Biograpy, [URL].