Lady Mary Seymour Countess of Winchelsea (d. 1672) Parents Frances Seymour, Duchess of Somerset William Seymour, 2nd Duke of Somerset Children Heneage Finch, 5th Earl of Winchilsea William Finch, Viscount Maidstone Frances Finch Siblings Lady Jane Seymour Frances Darcy, Countess of Holderness Henry Seymour, Lord Beauchamp Robert Seymour, Lord Beauchamp John Seymour, 4th Duke of Somerset William Seymour, Lord Beauchamp unknown Seymour Partners Heneage Finch, 3rd Earl of Winchilsea