Beatrice is the daughter of Isabel Fitz Piers (descended from Robert Grentesmaisnil of Grentesmaisnil in the Dukedom of Normandy) and Robert de Buslie (Lord of Tickhill, who came to England with William the Conqueror, and whose paternal line descends from the famed Lady Godiva, sister and heir of William Thorold. Lady Godiva married the Earl of Mercia, Leofric III, great-great-great grandson of Leofric I, Earl of Leicester in 750 A.D.)