Research Notes:

His parentage is confirmed by an undated charter under which his grandson “Faramus filius Willielmi Boloniæ” confirmed donations to Okeburn Priory, Wiltshire by “Gaufridus filius comitis Eustacii de Bolonia avus meus, et Willielmus de Bolonia filius ipsius pater meus”. Murray suggests that Geoffrey may have been born legitimate because (1) his descendants were known as "de Boulogne", (2) he married well, and (3) he was given the first name of his father's older brother. Murray further suggests that, if this is correct, he would have been Comte Eustache's son by Godgifu of England, whose marriage may have been annulled for consanguinity, which would have resulted in the bastardisation of their children. Geoffroy was mentioned in a writ of William I King of England dated [1066/71].

Lord of Carshalton. Domesday Book records land held from “Geoffrey son of Count Eustace” in Carshalton, Surrey, adding that "Geoffrey de Mandeville gave him this land with his daughter". William I King of England confirmed the donations in Balham and Walton by "Godfrey son of Count Eustace on behalf of his wife Beatrice, with the consent of Geoffrey de Mandeville", by charter dated to [1076/84]. He held the manor of Coton, Cambridgeshire from his father in 1086. He was in Palestine in 1100. ²