Upon the death of his first cousin once removed, John Hastings, 3rd Earl of Pembroke, on 30 December 1389, William inherited the lordship of Abergavenny, including Abergavenny Castle.
Following the death of his first cousin once removed, John Hastings, 3rd Earl of Pembroke on December 30, 1389, William acquired the Lordship of Abergavenny and its castle.