The extraordinary year 1215 has an unparalleled significance in English law and culture, and for two reasons: the proclamation of Magna Carta and the abolition of trial by ordeal. The former is by far the more famous, but the latter is just as significant.

The momentous confrontation at Runnymede between the barons and the king stemmed from need coupled with suspicion, and from the flawed personality of the king. In temperament John was unsuited to kingship. He had cunning but lacked confidence. He exercised power through the prism of paranoia. He thought others as base as himself, distrusting all the world and being distrusted in return. W. L. Warren says ‘he had the mental abilities of a great king, but the inclinations of a petty tyrant.’ Most would go further. John is generally considered to be the worst king England has ever had, and no other has ever borne his name. His failure was all the more apparent when contrasted with the enduring successes of his father Henry II, and with the martial reputation of his eldest brother Richard the Lionheart.

John succeeded to the throne in 1199 when Richard was killed at the height of his fame and in the midst of a siege. John proceeded precipitously to lose the Angevin empire his father had painstakingly built up and his brother had defended. He embarked on disastrous military ventures in France, which within five years had left him shorn even of Normandy itself. He desperately needed money to win it back, but doubted the barons' loyalty.