He was an archdeacon in the diocese of Coventry and Lichfield by 1221, and the treasurer of Lichfield Cathedral after 1223. He was also Archdeacon of Chester by 1222. He taught at Paris until 1229, when he moved to Oxford University to teach. He was named chancellor of Oxford University on 22 June 1231. He was Dean of Hereford by March 1231. At some point he wrote a commentary on Peter Lombard's theological work Sentences. Maidstone's work still survives in an extract in manuscript, as London, Gray's Inn, MS 14. Maidstone was elected Bishop of Hereford between 21 August and 30 September 1234 and consecrated on 12 November 1234 by Archbishop Edmund Rich at Canterbury. While bishop, he was sent on a diplomatic mission to Provence as an escort for King Henry III of England's bride. He was also involved in Welsh affairs, for in 1235, 136 and 1237 he took part in discussions with Llywelyn ab Iorwerth.
He was an archdeacon in the diocese of Coventry and Lichfield by 1221, and the treasurer of Lichfield Cathedral after 1223. He was also Archdeacon of Chester by 1222. He taught at Paris until 1229, when he moved to Oxford University to teach. He was named chancellor of Oxford University on 22 June 1231. He was Dean of Hereford by March 1231. At some point he wrote a commentary on Petra Lombard's theological work Sentences. Maidstone's work still survives in an extract in manuscript, as London, Gray's Inn, MS 14. Maidstone was elected Bishop of Hereford between 21 August and 30 September 1234 and consecrated on 12 November 1234 by Archbishop Edmund Rich at Canterbury. While bishop, he was sent on a diplomatic mission to Provence as an escort for King Henry III of England's bride. He was also involved in Welsh affairs, for in 1235, 136 and 1237 he took part in discussions with Llywelyn ab Iorwerth.

