The great charter – in Latin, Magna Carta – of 1215 was meant to curb the brutality and greed of King John. But it has come to symbolize the supremacy of the rule of law, and is thought of as the cornerstone from the British constitution.

In order to rule effectively all the feudal kings of England – the Normans and the Plantagenets – had to have the loyalty of their most powerful subjects, the barons. They depended on the barons to keep local law and order, to pay taxes for government, and to supply men and equipment for wars. When the monarch was strong, all went nicely, but when the king was weak, like Stephen, or unpopular and desperate for cash, like John, things got out of hand. Nobody liked John much.

When he died, the chronicler Matthew Paris said: ‘Foul as it is, Hell itself is defined by the presence of John’. His bad reputation seems pretty well deserved. He took up arms against his father; he tried to snatch his brother Richard’s throne although Richard was away crusading within the Holy Land; he divorced his wife to steal someone else’s fiancee; and he had his nephew and rival claimant for the throne, Arthur of Brittany, murdered. And they had been family! With people less dear to him he was really unkind. He demanded excessively heavy taxes and increased the amount of time that his vassals and their men had to fight for him.

He seized the lands of minors – children who had inherited prior to they were old enough to look after their properties – and only gave it back when he’d sold off everything worth having. He confiscated property and made owners pay to obtain it back, and he kept churches empty and took their incomes. John might have got away with all this if he had been successful in other ways. But he wasn’t. By 1204 he had lost nearly all the crown’s territory in France to Philip II, and his later efforts to obtain it back failed, culminating in the disastrous defeat from the English and their allies at Bouvines in 1214.

Endless disputes in Scotland, Ireland and Wales had been costly. He dragged England into a long running dispute with the Pope which resulted in the Pope first putting an interdict (a ban on baptisms, marriages or Christian burials) on to England, and later on his own excommunication. The Pope then declared the king deposed. Threatened with invasion from abroad and rebellion from his subjects at home, John gave in. He handed England and Ireland over to the Papacy, becoming the Pope’s vassal.