'Roger had one illegitimate child by an unknown mistress:
d) WILLIAM la Zouche. “Willielmus la Zouche, filius Rogeri la Zouche” confirmed donations to Swavesey Abbey, Cambridgeshire by “Rogeri patris nostri ac ... Alani Zouche avi nostri quondam comitis Britanniæ” by undated charter [citing Dugdale]. He was alleged ancestor of the Zouche family of Mortimer [citing Eyton].'