A condition of the peace treaty of 1217, under which Prince Louis resigned his claims to the throne and left England, was the confirmation of Magna Carta. Accordingly, the minority government of Henry III issued, in the king’s name, another new version of the charter. This is one of the four surviving originals. Since Henry still had no Great Seal, Magna Carta was authenticated with the seals of the papal legate, Guala (1150–1227), now detached, and the regent, William Marshal, Earl of Pembroke (1147–1219), now lost.
The 1217 charter largely followed the charter of 1216. It had, however, an important new clause on the running of the county and hundred courts, and concluded by saying that all the castles built during the war, without authorisation, were to be destroyed. The 1217 Magna Carta was also accompanied by a quite separate charter dealing with the royal forest. An original of the Forest Charter, preserved at Durham Cathedral, bears the date November 1217. Magna Carta itself was probably granted at the same time, even though the original documents do not bear a date. In fact, they were probably drawn up for a general distribution to the counties in February 1218, when it was thought confusing to give them the date of their original issue. Since this copy of Magna Carta was preserved at Oseney Abbey, outside Oxford, it may be the one sent to Oxfordshire.