His holding of Richard's Castle as a tenant-in-chief is considered to have made him a feudal baron.
[3] Osbern added to the lands he had held in 1066 not only by inheritance from his father, but also from his marriage, from royal gifts, and by enfeoffment from other landholders such as the bishop of Worcester and Roger de Montgomery, the earl of Shrewsbury.
[3] Osbern served as a royal judge in Worcestershire during the 1080s, and during the Rebellion of 1088 took the side of the baronial rebels against King William II.
[3] Osbern married Nesta or Nest, the daughter of Gruffydd ap Llywelyn[4] and Ealdgyth.
[3] Osbern and his wife had a son, Hugh fitzOsbern,[2] and a daughter, Nesta (or perhaps Agnes), who married Bernard de Neufmarché.