On this day in 1707 The Act of Union joined the Kingdom of England and Kingdom of Scotland to form the Kingdom of Great Britain.
The two countries had shared a monarch since the Union of the Crowns in 1603, when King James VI of Scotland inherited the English throne from his double first cousin twice removed, Queen Elizabeth I.
Although described as a Union of Crowns, until 1707 there were in fact two separate Crowns resting on the same head (as opposed to the implied creation of a single Crown and a single Kingdom, exemplified by the later Kingdom of Great Britain).
There had been three attempts in 1606, 1667, and 1689 to unite the two countries by Acts of Parliament, but it was not until the early 18th century that both political establishments came to support the idea, albeit for different reasons.
The Acts took effect on 1 May 1707. On this date, the Scottish Parliament and the English Parliament united to form the Parliament of Great Britain, based in the Palace of Westminster in London, the home of the English Parliament.
Hence, the Acts are referred to as the Union of the Parliaments. On the Union, the historian Simon Schama said “What began as a hostile merger, would end in a full partnership in the most powerful going concern in the world … it was one of the most astonishing transformations in European history.”