Using new material, including a hitherto unknown writ of King Henry III from 1253, this article explores the divisions which opened up between English secular and ecclesiastical reformers in the twelve-fifties. It shows that in securing the confirmation of Magna Carta in 1253, the church gained far less than it had hoped, largely because the laity in parliament had limited sympathy with its wider claims. For the same reason, the king, magnates and people in parliament rejected the church's version of the sentence of excommunication which supported the 1253 confirmation of the charter. This division foreshadowed the events of 1258 when lay and ecclesiastical reformers went their own separate ways, with the result that the revolutionary reforms of 1258, which stripped the king of power, had neither ecclesiastical content nor support. They were thus very different and much weaker than Magna Carta, which had both.