 He was summoned to Parliament on 23 July 1392 as "Willilmo Beauchamp de Bergavenny", by which he is held to have become Baron Bergavenny, a barony by writ.In 1399, he was appointed Justiciar of South Wales and Governor of Pembroke.He entailed the castle and Honour of Abergavenny on the issue male of his body, with remainder to his brother Thomas de Beauchamp, 12th Earl of Warwick and his heirs male; his wife enjoyed it in dower until her death in 1435.