On Hogmanay, Edinburgh becomes a city of the world. The Scottish capital’s annual New Year celebrations attracted 400,000 partygoers until the council limited the numbers to 180,000 for safety reasons in 1998. This year had special poignancy. For as they linked arms and sang Auld Lang Syne, many were aware that this could be the last New Year that Scotland remains linked to the UK.

In a few months' time, the most successful political union the world has ever seen, the United Kingdom, which once had an empire spanning a quarter of the globe, could be no more. On September 18, 2014, Scots will be asked a simple question: should Scotland be an independent country? Most are expected to vote No, which is why the British state appears unruffled. But there is no guarantee that the 300-year-old Union will survive.