Isabel was born between 1226 and 1230, her father was William de Warenne, 5th Earl of Surrey and her mother was Maud Marshal, Countess of Norfolk, both of whom had been widowed previously and married in 1225.
Patent Rolls show that she had provision to remain unmarried if she chose but would have had to make a payment to Pierre to be released.
[3] In 1252, she visited the Cistercian Abbey at Waverley where she consulted with the abbot and granted 4 marks and a cask of wine to the monks.
However Thomas was a tenant of de Warenne's, and owed her a quarter of a knight's fee, so she requested the value from the King.
[3] Henry would pay back the debt a year later, and forgive the fine that she had been charged in appealing the case,[1] providing that 'she says nothing opprobrious to us as she did when we were at Westminster'.