The seal of Stephen Langton, Archbishop of Canterbury (1150-1228), is notable for containing on its reverse a depiction of the martyrdom of Thomas Becket. Langton was instrumental in securing peace between King John and the barons in 1215, and it may have been at his instigation that the Great Charter’s first clause, confirming the liberties of the English Church, was inserted. Recent research has also suggested that the damaged 1215 Magna Carta (British Library Cotton Charter XIII 31A) was preserved at Canterbury Cathedral in the Middle Ages. The charter to which this seal is attached contains Langton’s confirmation of the privileges of the Cistercian Order in England, as conceded by Pope Honorius III (r.1216–27). By featuring an impression of Becket’s martyrdom on his seal, Langton emphasised his connection with his murdered predecessor, and the desire, as expressed in Magna Carta, that the Church remain free from royal interference.