"Magna Carta?

".........its purpose was to take power out of the hands of the king and put it in the hands of the barons."

That might well have been it's purpose, only thing was that was not the way it was written and the "unintended" and unconsidered fall-out of that was that via the Magna Carta the PEOPLE of England acquired rights. The power of the Monarch was not formally shackled until 1688 and the arrival of William of Orange.

"In the United Kingdom, the Bill of Rights is further accompanied by Magna Carta, the Petition of Right, the Habeas Corpus Act 1679 and the Parliament Acts 1911 and 1949 as some of the basic documents of the uncodified British constitution. A separate but similar document, the Claim of Right Act 1689, applies in Scotland. The Bill of Rights 1689 was one of the inspirations for the United States Bill of Rights."