Research Notes:
"Saher de Quincy, Earl of Winchester, married Margaret de Beaumont."[1]
Margaret, daughter of "Robert [de Beaumont], Earl of Leicester, d. 1190" and "Pernel de Grandmesnil" married "Saher de Quincy, Earl of Winchester." [2]
[1] Douglas Richardson and Kimball G. Everingham, Magna Carta Ancestry: A Study in Colonial and Medieval Families, 2nd editon, 4 vols. (Douglas Richardson, 2011), 3:403, [GoogleBooks].
[2] George E. Cokayne and Vicary Gibbs, ed., The Complete Peerage, rev., Vol. 7, Husee to Lincolnshire (London: St. Catherine Press, 1929), 520.