RUNNYMEDE, ENGLAND - JUNE 15:  (L-R) The Archbishop of Canterbury Justin Welby, Britain's Prime Minister David Cameron, Queen Elizabeth II, Prince Philip, Duke of Edinburgh, Prince William, Duke of Cambridge and Princess Anne, Princess Royal attend a service to mark the 800th anniversary of Magna Carta on June 15, 2015 in Runnymede, United Kingdom. Members of the Royal Family are visiting Runnymede to attend an event commemorating the 800th anniversary of Magna Carta. Magna Carta is widely recognised as one of the most significant documents in history. Its influence, as a cornerstone of fundamental liberties, is felt around the world in the constitutions and political traditions of countless nations. (Photo by Stefan Wermuth - WPA Pool / Getty Images)