Due to his local knowledge of the Welsh Marches he was an important advisor to Edward I of England during his conquest of Wales. During Edward's first campaign in 1277 he was put in charge of Oswestry Castle, Dinas Bran, Builth and Montgomery Castle - the Welsh inhabitants living near these castles regarded him as a tyrant.
Due to his in-depth knowledge of the Welsh Marches, he held significant influence as an advisor to Edward I of England during the conquest of Wales. In 1277, Edward entrusted him with responsibility for Oswestry Castle, Dinas Bran, Builth, and Montgomery Castle - the local Welsh population viewed him as a harsh ruler.