Margery was the eldest of four daughters of Bartholomew, first Lord Badlesmere, stated to be aged 32 when she became heir to her brother, Giles. who died 3 February 1342/43. As the widow of William de Ros, she had a royal license to marry whom she would of the King's allegiance, which license, dated 6 Mar 1350/51 was to Sir Thomas de Arundel, who was killed shortly thereafter. She married thirdly (as probably his third wife), Sir John Avenal, the King's Lieutenant in Brittany, from whom she sued for divorce in April 1355.