After the hurdles of decolonisation, apartheid and human rights, the Commonwealth emerges as a voluntarist group of 54 countries, half of them small or island nations, which is not entirely sure how to define itself. For much of the last decade, it was a UK legacy stuck in the attic gathering dust. But the soft power of such a group is tangible enough. The advantages of mutual prosperity have been lost sight of, although trade within the Commonwealth has increased. A study by the Royal Commonwealth Society found that this was because member states believed each other to be safer bets than non-members. But it’s not all about export credit guarantees. The traditions and institutions of the club are important, too. When the Commonwealth secretary general, Kamalesh Sharma, suggested that Scotland might have to reapply for membership if it left the UK, the next host of the Commonwealth Games in Glasgow was up in arms.