General Notes

He [William de Blois] married Isabel, only daughter and heir of William (DE WARENNE), 3rd EARL OF SURREY, by Ela. He died s.p. as above in October I 159 and was buried in the hospital of Montmorillon in Poitou. Isabel survived him and was sought in marriage by Henry Il's brother William, but Archbishop Beket opposed the match on the ground of consanguinity, and she married, 2ndly, the King's illegitimate half-brother, Hamelin. [Complete Peerage XII/1:497-9, (transcribed by Dave Utzinger)]

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He [Hamelin Plantagenet] married, in 1164 (probably in April), Isabel, widow of William (OF BLOIS) 4th EARL OF SURREY, and only daughter and heir of William (DE WARENNE), 3rd EARL OF SURREY, all above-named. He died 7 May 1202 and was buried in the Chapter House at Lewes. Isabel survived him and made gifts for the soul of her late husband to the priory of St. Katherine, Lincoln, and to Lewes Priory. She was living in April 1203 but died probably soon afterwards, possibly 12 July 1203, and was buried in the Chapter House at Lewes (g).  [Complete Peerage XII/1:499-500, (transcribed by Dave Utzinger)]

(g) By her 2nd husband she had issue, a son William, 6th Earl, and 3 daughters: (1) Ela, who m. 1stly Robert de Newburn, of whom nothing is known, and 2ndly, William FitzWilliam of Sprotborough; (2) Isabel, who m. 1stly Robert de Lascy, and 2ndly Gilbert de Laigle, lord of Pevensey; (3) Maud, who m. 1stly  Henry, Count of Eu and lord of Hastings, and 2ndly Henry d'Estouteville or de Stuteville, of Eckington, co. Derby, and Dedham, Essex, lord of Valmont and Rames in Normandy.