Gilbert was a Hispano-Norman nobleman who was Count of Gravina from around 1159 and, during the regency of Margaret of Navarre, also count of Loritello and royal master captain or great constable in Apulia and the Terra di Lavoro until his exile in 1168. His father Bertram was the illegitimate son of Count Rotrou II of Perche. Through Queen Margaret's maternal kin, Gilbert was a distant but genuine relative of Margaret of Navarre, the queen of Sicily.