No house had played a greater part in the overthrow of Richard, or had been more richly rewarded by the new king.

But old grudges existed between the house of Percy and the house of Lancaster.

The Earl of Northumberland had been at bitter variance with John of Gaunt; and though a common dread of Richard's enmity had thrown the Percies and Henry together the new king and his powerful subjects were soon parted again.
Henry had ground indeed for distrust.

The death of Richard left the young Mortimer, Earl of March, next claimant in blood of the crown, and the king had shown his sense of this danger by imprisoning the earl and his sisters in the Tower.

But this imprisonment made their uncle, Sir Edmund Mortimer, the representative of their house; and Edmund withdrew to the Welsh Marches, refusing to own Henry for king.