Which British treaty or document changed the course of history the most?

Sealed at Runnymede by King John, it planted the seed of the idea that even monarchs are subject to the law. Its principles still echo through constitutions worldwide.

The treaty that merged the English and Scottish parliaments, forging a single state and reshaping the political map of these islands. Its legacy is still hotly debated north of the border.

Passed after the Glorious Revolution, it curbed royal power and laid the foundations of constitutional monarchy. Much of what we take for granted in Westminster begins here.

The painstakingly negotiated deal that brought an end to decades of violence in Northern Ireland. It remains a fragile but extraordinary achievement of modern diplomacy.

Signed in the Hall of Mirrors, the treaty that ended the Great War and, many argue, sowed the seeds of the next one. British negotiators shaped its terms and its consequences.