When King John signed the magna carta, what right was granted to The Great Council?

The right was to renounce the oath of allegiance to the king in pressing circumstances and to pledge allegiance to the council and not the king.

The Great Council was comprised of the most powerful men in the country. Its goal was to exist for the benefit of the state rather than in allegiance to the monarchy. The Council itself was seen as the first crucial step towards the development of a parliament. It was also responsible for taxation.

The Great Council only existed to give input and opinion on the kingdom as a whole. The king would summon the leading churchmen and barons to meet at a specific time and place with at least 40 days' warning.

The biggest power of the Council was to meet and operate outside of the authority of the king and to concentrate on a state rather than the monarchy.