Sources

1) Source: The Berkeley Estate "Robert FitzHarding and Roger de Berckele. Agreement made in Robert's house at Bristol, in the presence of Henry duke of Normandy, for Robert's son Maurice to marry Roger's daughter, with Slimbridge, being £10 worth, for her portion, and for Roger's son Roger to marry Robert's daughter, "Dated: after 1153. Reference: BCM/A/1/43/62 (Data from direct source)
2) Source: The Berkeley Estate "Alice widow of Maurice de Berkeley and Thomas de Berkeley her son."Dated: 1190-1215. External Link
http://discovery.nationalarchives.gov.uk/details/r/ba25e873-4977-4843-a865-230e31e7eba3. Reference: BCM/A/2/17/6 (Data from direct source)
3) Source: Chancery: Inquisitions Post Mortem, Series I, Edward II "John Waleraund alias Waleround (Walerand), an idiot deceased...Sistone. The manor (extent given) with 4l. rent in Cubberlegh, including a pasture at Doynton, and a rent of a hen called ‘wodehen,’ held by the said Robert for a term of years which has passed, by the demise of Alice his sister, of the heir of William de Berkeleye in chief, who is in the king’s wardship, by service of 1 knight’s fee; which manor and rent ought to revert to Alan son of Alan Plokenet, son of Alice, daughter of Isabel, daughter of Thomas de Rochesford and Agatha his wife, because Roger de Berkeleye gave the same to the same Thomas and Agatha his daughter, in free marriage, and the said Alice delivered them to Robert Waleraund for a term of years as abovesaid."Dated: 1308. External Link
http://discovery.nationalarchives.gov.uk/details/r/C9671512. Reference: C 134/11/1 (Data from secondary evidence)