Lady Mary Margaret Stanley (1801-1858) (1801–1858) Parents Elizabeth Farren Edward Smith-Stanley, 12th Earl of Derby Children Lady Katherine Egerton Seymour Egerton, 4th Earl of Wilton Lady Alice Egerton Elizabeth Egerton Arthur Egerton, 3rd Earl of Wilton Siblings Lady Elizabeth Stanley Edward Smith-Stanley, 13th Earl of Derby Lady Charlotte Stanley Partners Thomas Egerton, 2nd Earl of Wilton