The inhabitants of Britain the island containing England, Wales and Scotland live in a state of some confusion over their group identity. Their cars, travelling abroad, display the letters GB (for Great Britain). Their diplomats, at international conferences, sit behind the letters UK (for United Kingdom).
Given the centuries of hostility between Scotland and England, with warfare even in the 17th century under a shared Stuart king, the union of the two kingdoms seems to come with surprising suddenness.
It has been under discussion for a considerable time, for James VI and I tries to achieve it after inheriting the English throne in 1603. But the idea meets with little favor (although imposed during the Common wealth) until the early 18th century.