Robert de Grey, 4th son of Henry de Grey, of Thurrock, obtained from his brother, Walder de Grey, Archbishop of York, a gift of the major part of the lordship of Rotherfield, co. Oxford. [Sir Bernard Burke, Dormant, Abeyant, Forfeited and Extinct Peerages, Burke's Peerage, Ltd., London, England, 1883, p. 24, Grey, Barons Grey, of Rotherfield, co. Oxford]
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Note - As pointed out in the note appended to the article on Grey of Codnor, Anschetil, whose origin is to be sought in Greye-sur-mer, had in Oxfordshire at the time of the Domesday Survey a considerable holding, which included Rotherfield. . . G. A. Moriarty, who has shown that Ralph Murdac of Broughton held lands in Standlake and Rotherfield in right of his wife, Eve de Grey, who appears to have been an heiress. She (who m., 2ndly, Andrew de Beauchamp) d. about 1242, leaving daughters and coheirs. It is not the purpose of this work to trace the history of families to their origin, where no peerage as yet existed, but the persistent attempt to make Henry de Grey of Grays Thurrock father of all Greys necessitates some attempt to show that he had nothing to do with the paternity of Walter de Grey, Archbishop of York, or of Robert de Grey of Rotherfield, who was the Archbishop's brother. Their mother, Hawise de Grey, was living at the same time as Iseude de Grey, wife of the said Henry and mother of Richard de Grey of Codnor and Grays Thurrock, of John de Grey of Shirland and Wilton, and of William de Grey of Sandiacre. Nor does the relationship between Henry de Grey and the Archbishop become apparent, seeing that Robert de Grey is disctincly mentioned as son and heir of Hawise de Grey, while the descendants of Henry de Grey bore the undifferenced arms and appear to have been regarded as the senior line.
During the lifetime of Eve de Grey, Rotherfield was acquired by Walter de Grey, Archbishop of York, who settled it upon his brother Robert de Grey. [Complete Peerage VI:150-1 note]