His daughter, Joan of Cornwall, married Sir John Howard, from whom the Howard family, Dukes of Norfolk, are descended. The arms of de Cornwall were: Argent, a lion rampant gules ducally crowned or a bordure engrailed sable bezantee, being the arms of Richard, 1st Earl of Cornwall with difference a bordure engrailed.
His daughter, Joan of Cornwall, married Sir John Howard, from whom the noble lineage of the Howards, Dukes of Norfolk, originates. The coat of arms of de Cornwall included: Argent, a lion rampant gules ducally crowned or a bordure engrailed sable bezantee, which was identical to the arms of Richard, 1st Earl of Cornwall with an additional difference in the bordure.