On the death of her first husband Count Robert of Meulan and Leicester in 1118 Isabel promptly married Earl William II de Warenne (died 1138) and since Gundreda had an infant daughter by 1138 it is most likely she was the eldest child of the marriage.

The marriage tied Earl Roger into the Beaumont clique dominant at the court of King Stephen of England between 1135 and 1141.

For Waleran the marriage helped secure his position in the English west midlands where the king had made him earl of Worcester.

[1] In 1138 Gundreda's infant daughter Agnes was similarly employed to settle a local war in Warwickshire by a marriage to Earl Roger's rebel vassal, Geoffrey II de Clinton of Kenilworth, in a deal ironed out by Gundreda's father, Earl William.

[2] There are indications that Gundreda was dominant in her husband's council, occupying a leading place in his charters and notoriously forcing his change of side in 1153 to support Henry Plantagenet and abandon King Stephen by conspiring to surrender Warwick Castle to the Angevin party, a manoeuvre that is said to have caused the loyalist Earl Roger's death by a seizure when he heard of it.