Father William de Brewes, Lord of Abergavenny, Brecon, & Ower Gwent, Seigneur de Briouze b. c 1144, d. 9 Aug 1211
Mother Matilda (Maud) de St. Valerie b. c 1138, d. 1210
Margaret de Brewes was born circa 1177 at Abergavenny, Brecknock, Wales. She married Sir Walter de Lacy, Sheriff of Herefordshire, Lord of Meath, son of Hugh de Lacey, Lord Meath, Justice of Ireland and Rose of Monmouth, on 19 November 1200.
Sir Walter de Lacy, Sheriff of Herefordshire, Lord of Meath b. c 1172, d. Feb 1241