Richard Beauchamp survived only 8 years after succeeding to the lordship; he died in 1422. A year later his widow, Isabel, still only 23 years old, married his kinsman of the same name - Richard Beauchamp Earl of Warwick. Warwick had been a trusted counsellor of King Henry V, who had appointed him, on his deathbed in 1422, to be governor of his infant son, King Henry VI.
The final defeat of Owain Glyndwr, of whom no more had been heard for some years, and the failure of the Welsh to mount a further offensive, saw the prospect of peace in Glamorgan. Isabel's second husband now prepared to move from the safety of the Keep, embarking upon the construction of new lodgings against the West Curtain Wall.
The core of the present house therefore dates from this period (1423-39) and may have consisted of further buildings that have now vanished. However, the surviving residential block the Earl constructed was sophisticated and in the latest taste, being stylistically related to the Rose Tower at Windsor Castle.