daughter of William de Longespee Earl of Salisbury (illegitimate son of Henry II and Ida de Tosny Bigod) and Ela Devereux Countess of Salisbury:

http://fmg.ac/Projects/MedLands/ENGLISH NOBILITY MEDIEVAL1.htm:

ELA Longespee (-9 Feb 1298, bur Oseney Abbey, Oxon). The Book of Lacock names “Isabellam de Vescy…Elam…Idam de Camyle” as the daughters of “Guillelmus Longespe ex…Ela”, adding that Ela married “Comes Warwik, et postea Philippus Basset” but was childless[1366].

m firstly THOMAS de Warwick Earl of Warwick, son of HENRY Earl of Warwick & his first wife Margery de Oilly (-26/27 Jun 1242, bur Warwick St Mary).

m secondly ([25 Nov 1254/23 Mar 1254/5]) Sir PHILIP Basset of Wycombe, Bucks (-29 Oct 1271, bur Stanley, Wilts). Justiciar of England. No issue.