This Thursday is decision day for the UK and Europe. In the first of a special range of articles, we reflect on a remarkable creation of post-war idealism and what leaving it might mean

For  1,500 years the inheritors of the Roman Empire have been fighting with one another and in so doing have built a shared history and a shared political, intellectual and artistic culture that is unique for its variety in continuity. After 1945, they gradually resolved that what they shared was best perpetuated not by war but by peaceful economic and cultural interchange.

Encouraged by Winston Churchill to found a United States of Europe, they set out on a rather more cautious path, via the preparatory Common Market/European Economic Community (EEC), to the European Communities (EC), the explicitly political federation that the United Kingdom joined in 1973, and on to the European Union (EU), founded in Maastricht 20 years later.

Churchill did not expect Britain to be a member of Europe’s United States because he still presumed that Britain’s destiny lay with its empire – for which, in 1940, he had contemplated a future lasting 1,000 years. Those who now wish the UK to leave the EU still share that presumption, and they may still invoke Churchill’s authority, even though, since he spoke, the empire has been dismembered and swallowed up by a worldwide economic system that is even more ­comprehensive.