On the banks of the River Thames, 800 years ago, history was made. A group of barons in Runnymede made King John, widely regarded as one of the weakest monarchs of all time, sign a document known as the 'Magna Carta'.

This charter decreed that everyone, even the king, was subject to the law. Julian Harrison, curator of the 'Magna Carta: Law, Liberty, Legacy' exhibition currently on at the British Library, explains the significance of this momentous occasion.

"The Magna Carta is one the most famous documents in the world. When it was first granted by King John in 1215 it was effectively a peace treaty between the king and his barons.

"Since then in the following centuries it has gained new impetus. People have interpreted it as a document for human rights.

"The Magna Carta contains one really famous clause, which effectively states that no man should be arrested or imprisoned save by the lawful judgement of their equals or by the law of the land. That's really important and something we often take for granted today. But over the centuries that clause has been used by people such as Thomas Jefferson, Nelson Mandela and Eleanor Roosevelt to fight for their rights and freedoms."

'Magna Carta: Law, Liberty Legacy' is open at the British Library until 1 September. The British Library has also launched an 'Internet Magna Carta' where people can vote online about what should be included in a Magna Carta for the digital age.

Music: "Pippin the Hunchback" Kevin MacLeod (incompetech.com)