Therefore, the Earl of March not only represented one of the chief Anglo-Norman lordships in Ireland in right of his wife Philippa, but Philippa's line was also the second most senior line of descent in the succession to the crown, after Edward, the Black Prince and his son, King Richard II of England. John of Gaunt, younger brother of Prince Edward, had become the 1st Duke of Lancaster and thus the source of the House of Lancaster's claim to the throne.