LONDON • The claim that Britain is a country in decline and that it has willingly written itself off the top league of nations is by now so widespread as to be accepted wisdom.

On an almost daily basis, one gets some media commentator somewhere bemoaning the supposed fate of the nation which used to run the biggest empire the world has ever known, but has now been reduced to the status of a windswept group of islands on the edge of Europe, obsessed with its own internal squabbles, unable and unwilling to deal with trends in the wider world.