His rival, Somerset, belonged to the Beaufort family who, like Henry, were descended from John of Gaunt, Edward III's fourth son, though by his former mistress, Katherine Swynford.
His rival belonged to the Beaufort family. This Beaufort family were descended from John of Gaunt though by his former mistress. This was like Henry. Katherine Swynford was his former mistress. Edward III's fourth son was Gaunt. His rival was Somerset.