William de Ferrers, 5th Earl of Derby English Earl (1193–1254) Parents Agnes of Chester William de Ferrers, 4th Earl of Derby Children Agnes de Ferrers Sibyl de Ferrers Agnes Ferrers Agatha Ferrers Joan de Ferrers Maud Ferrers Joan de Ferrers William Ferrers Robert de Ferrers, 6th Earl of Derby Isabel Ferrers Alianore de Ferrers Elizabeth Ferrers Siblings Berta (?) Agnes de Ferrers Partners Margaret de Quincy, Countess of Derby Sibyl Marshal
