Gideon Rachman is chief foreign affairs columnist for the Financial Times.

It is the quote that has launched a thousand articles. Dean Acheson’s remark that ‘Britain has lost an empire and not yet found a role’ was made fifty years ago, in 1962. Ever since, it has been held up as a uniquely pithy summary of the Great British foreign policy dilemma.

If, as seems likely, the UK is about to enter another agonised debate about its relationship with the European Union, the Acheson quote is bound to be rolled out yet again.

In Brussels, Britain’s coolness towards the European project is often attributed to some form of post-imperial delusion. ‘The British still think they are a great power’, so it is said, ‘that is why they behave in this peculiar way.’ At some point, somebody will add sagely, that Britain’s ‘special relationship’ with the United States is not all it’s cracked up to be. And, as for the Commonwealth … don’t even get them started.

But the idea that Britain is uniquely loaded down by historical baggage does not make much sense in a European context...