Oliver [who had livery in 1217] was son and heir of Oliver (aged 24 in 1186, m. Amabel, and d. in or bef. 1201), son and heir of John (who had livery in 1167-8, and d. 6 Nov 1183), by Alice, sister of Ralph Murdac. John was son and heir of Walter son and heir of Ralph (who m. Basilie), son and heir of Walter d'Aincurt, the Domesday lord of Blankney. [Complete Peerage IV:118 note (c)]
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Oliver, 5th baron, who, by his wife Annabella, had a son Oliver. [Sir Bernard Burke, Dormant, Abeyant, Forfeited and Extinct Peerages, Burke's Peerage, Ltd., London, England, 1883, p. 170, d'Eyncourt, Barons d'Eyncourt]