We have this unique papal bull annulling Magna Carta, issued on 24 August 1215, is display in the British Library's 2015 Magna Carta: Law, Liberty, Legacy exhibition. When taking guests around, I often joke on reaching the bull that here the show ends, despite the fact that they have 800 years of Magna Carta's legacy still to encounter. (A brief history lesson: after King John died in October 1216, with many of the barons again in rebellion and a French army having invaded England, and with a new 9-year-old king, Henry III, on the throne, a revised version of Magna Carta was issued in order to get the barons back on side, reviving the document in a single stroke.)
King John was a particularly devious ruler, and he clearly believed that, by sending messengers to his overlord, the Pope, the kingdom of England would be rid of Magna Carta. John was right, to a certain degree; but little did he realise that Magna Carta incorporated an adaptability that made it useful in many different ways to succeeding generations. I suspect in any case that both John and the barons would be horrified if they knew we were celebrating their peace treaty 800 years after that event (the terms of Magna Carta in 1215 applied only to the elite of society, the nobles and barons). Pope Innocent may have shared their opinion, but his attempt to stop the Great Charter in its tracks only had limited effect.