 He obtained from FitzHamon the lordship of Neath, Glamorgan, in which he built Neath Castle and in 1129 founded Neath Abbey.Richard de Grenville is by tradition the founder and ancestor of the prominent Westcountry Grenville family of Stowe in the parish of Kilkhampton in Cornwall and of Bideford in Devon.By tradition Richard de Grenville is said by Prince (died 1723), (apparently following "Fuller's Worthies")) after he had founded Neath Abbey and bestowed upon it all his military acquisitions for its maintenance, to have "returned to his patrimony at Bideford where he lived in great honour and reputation the rest of his days".