Keats-Rohan states, [1]
Willelm Filius Baderon
Son of the Breton Baderon of La Boussac (near Dol, dépt. Ille-et-Vilaine), succeeded his father and uncle Wihenoc as castellan of Monmouth before 1086 as a young man (Book of Llan Daw, pp. 277-8). His charters to his father and uncles's priory of St Mary, Monmouth, a cell of St Florent de Saumur, contain much information about his family and followers (CDF, 1133-1138). He was married to Havise, by whom he had issue Baderon, his successor, Robert Walensis, and two daughters, Jueta [Judith] and Advenia; one of his daughters was the mother of Richard de Cormeilles (ibid., 1139). His brothers Robert and Payn occur in the same charters. He died at an unknown date before 1144. Sanders, 65; H. Guillotel, 'Une famille bretonne au service du Conquérant: les Baderon', Droit privé et institutions régionales: Etudes historiaues offerts à Jean Yver (1976), 361-6.
Research Notes:
Hubert Guillotel discusses the Baderon family. [2]
[1] K. S. B. Keats-Rohan, Domesday People, A Prosopography of persons occurring in English documents, 1066-1166 (Boydell & Brewer Ltd, 1999), 484, [GoogleBooks].
[2] Hubert Guillotel, "Une famille bretonne au service du Conquérant : les Baderon," Droit Privé et Institutions Régionales: Études offertes à Jean Yver, (Mont-Saint-Aignan: Presses universitaires de Rouen et du Havre, 1976), 361-367, [OpenEditionBooks].