Margaret Willoughby, Lady Willoughby English noblewoman, daughter of Lord Deincourt (died in or before 1333) Parents Sir Edmund Deincourt, 1st Lord Deincourt Children Joan Willoughby John Willoughby, 2nd Lord Willoughby Siblings Isabel Deincourt John Deincourt Partners Robert de Willoughby, 1st Baron Willoughby de Eresby