On 1 January 1306, Pope Clement V publicly revoked the concessions that had been forced upon Edward I in the Articuli super cartas. Had Edward I allowed these concessions to be added to Magna Carta, it would have been much more difficult to have them revoked in this way (SC 7/10/36).
Transcript
Bishop Clement, the servant of the servants of God sends greetings and his apostolic benediction to our venerable brother, the bishop of Worcester.
We order that you publish in your churches our revocation of the concessions forced upon Edward, king of England, whilst he was in Flanders and absent from the kingdom. Publish also in your churches the absolution of King Edward from sentences of excommunication incurred because of his failure to observe the aforesaid concessions.
Given in Lyon, on 1 January 1306.