The term ‘soft power’ was made famous by Harvard academic Joseph Nye in a 1990 article on leadership. In fact, long before then writers had pointed to a third kind of power, beyond those provided by armies and money. In 1939, for example, E H Carr wrote that ‘power over opinion’ could be as important as economic and military power. Today, the Anholt-GfK Roper Nation Brands Index and the more sophisticated Portland Soft Power 30 league table both measure this kind of power, with each nation’s relative ‘likeability’ being fundamental to their ranking. Robert Winder reproduces the latest tables in an appendix.

Weighing soft power is harder than counting ballistic missiles or warships, or for that matter ranking countries by GDP per capita. It is based on more than simple diplomacy, since it also derives from commercial products, culture and such intangibles as, for instance, the way in which, during the recent Rugby World Cup, Japanese rugby fans sang the national anthems of other countries and then picked up the litter left by foreign supporters. Soft power is akin to commercial branding. Its success depends on how convincing foreigners find the stories countries tell about themselves. That includes their histories, which can sometimes be highly contentious, as Britain and Japan know.

It is related to GDP, which is affected by such things as how many foreign students a country attracts – they earn the UK £6.7 billion per annum, a figure that dwarfs the £2 billion the BBC earns from overseas sales – and how many tourists visit galleries and museums.