The museum has held up the loan to Iran’s National Museum of the Cyrus Cylinder, a cuneiform document inscribed in clay in 539BC by Cyrus the Great, King of Persia, to commemorate his conquest of Babylon. The reason for the delay is the discovery of two fragments from the cylinder that could greatly elucidate its purpose.

The spat is more about the petulance of the theocrats in Tehran who have lost legitimacy after brutally stealing last summer’s presidential elections and crushing dissenters who refuse to be cowed. The UK, as a mega-meddler in Iran over the past two centuries, is being used by the mullahs as a decoy target for nationalist dissent, and as a proxy “Little Satan” for the “Great Satan” of the US.

It is a bit rich that this affair involves Mr MacGregor, the most open of directors who pursues a democratic form of cultural globalisation and sees his institution as a museum for the world – an enduring achievement of the European Enlightenment in which everyone, from everywhere, has access to the history of humanity.

The Cyrus Cylinder is a milestone in that history, often described as the first charter of human rights: it prescribes the return of deported peoples (including the Jews) to their homelands, and declares that all should be free to practise their own religions. The new fragments apparently add to the sense that this was a liberating proclamation. Little wonder it unsettles the dictators in Tehran.