Joan de Ferrers (1248-1310) (1248–1310) Parents William de Ferrers, 5th Earl of Derby Margaret de Quincy, Countess of Derby Children Alice Berkeley Thomas de Berkeley Isabel de Berkeley Margaret de Berkeley Maurice de Berkeley, 2nd Baron Berkeley James Berkeley John de Berkeley Siblings Joan de Ferrers Alianore de Ferrers Elizabeth Ferrers Robert de Ferrers, 6th Earl of Derby Isabel Ferrers Agatha Ferrers Sibyl de Ferrers William Ferrers Agnes de Ferrers Maud Ferrers Agnes Ferrers Partners Thomas de Berkeley, 1st Baron Berkeley Sir Robert Aguillon