[2] The fact that aunt and niece had identical names, Isabel de Bolbec, and were successively countesses of Oxford and heiresses of Whitchurch has led to confusion between the two women.

In 1215, Robert settled his sister-in-law's dower by lot, the earl drawing two knights' fees for every one drawn by Alice.

[citation needed] Robert joined the disaffected barons who met at Stamford and forced King John to issue Magna Carta at Runnymede on 15 June 1215.

Together with other Magna Carta barons, he was excommunicated as a rebel by Pope Innocent III on 16 December 1215, and joined them in offering the crown to Prince Louis of France.

He was buried at Hatfield Regis Priory, where either his son, Hugh de Vere, 4th Earl of Oxford, or his grandson, Robert de Vere, 5th Earl of Oxford had an effigy erected in which he is depicted in chain mail, cross-legged, pulling his sword from its scabbard and holding a shield displaying his de Vere arms.