The European Union is facing today a major challenge since its creation. Brexit could mean not only the reversal of the steady enlargement of its dimensions – from 6 to 28 member-states – but also the beginning of an inexorable decline leading to its disintegration. However, few today seem to recollect that it was precisely the British who were the first to elaborate the political culture which has inspired the European construction – democracy and federalism – and first who tried to realize – in June 1940 – a European federation on the basis of the Anglo-French Union. Following the entry of the United Kingdom, the European Community was never the same again. The actual political phase of the process of European integration was inaugurated, and enlargement reinforced the feeling in European citizens of being part of a functioning European political system. The British brought to the Community citadel the specific values of their political tradition, such as representative democracy and federalism. It was therefore no coincidence that the Paris summit of December 9–10, 1974 – the official entry of the United Kingdom took place on January 22, 1972 – decided the direct elections of the European Parliament in 1979, and the creation of the European Council that it would have to meet at least three times a year.