"David the Bastard, alias le Clerc [son of William de Malpas by Beatrix de Montalt], intruder into his father's moiety of Malpas" married "Constance, daughter of Owain Kevelioe, prince of Powys."
Another compiler indicates that Constance was the granddaughter of Owain Cyfeiliog (assumed to be the same as Kevelioe) rather than his daughter. The dates fit better for this (Owain died 1197 and Gwenwynwyn died 1216).