Here we go again. The debate about the Parthenon Marbles in the British Museum — should they, shouldn’t they be returned to Greece, where a sparkling purpose-built museum overlooking the Acropolis from which the sculptures were wrenched by Lord Elgin from 1801-05 sits waiting for them — seems to go on for ever.

It was in the 1980s that Melina Mercouri, then Greece’s minister of culture, launched a passionate campaign for their return; she never stopped trying until her death in 1994. An official request from Greece to the UK parliament was refused — but has remained open ever since. And it was more than a decade ago that my then colleague Peter Aspden, himself half Greek and a fervent Returner, put forward in this paper a very considered practical plan which included loan and sharing arrangements, and an ownership structure that would save face all round. It could have saved an awful lot of trouble — but some people just won’t listen, will they?

This time round, the issue has been reignited by a back-and-forth between Jonathan Williams, British Museum deputy director, after he came out with a super-cautious statement about a possible new “cultural exchange” agreement regarding the Parthenon sculptures, and Professor Nikolaos Stampolidis, director of the Acropolis Museum. The latter’s response was far more robust, escalating the debate to global proportions: “The issue of the sculptures is not bilateral, it is a matter of international, western culture, not only of Europe but also . . . of all the democracies,” Stampolidis said.

There are marble sculptures from the Parthenon in many places — the Louvre, the Vatican, museums in Copenhagen, Vienna and Munich — but it is the British Museum’s haul that matters most. Not just in terms of quantity but for the sheer immorality and arrogance of their plunder.

In every one of the multiple restitution and repatriation cases now so frequent across the globe, this aspect — the way it happened — lends a strong weighting to the rights and wrongs involved. But these cases are sometimes fiendishly complicated, tying up lawyers for years.

When it comes to the legal, rather than the emotional or moral, aspects of restitution claims, antiquities and ancient artefacts are often simpler. And the Parthenon Marbles are probably the most clear-cut case of all: they answer all the test questions. We know where they originally were, when and how they were removed. There’s no gap in the chain of ownership to cast doubts. And we know that if (I should say when) they’re returned, they will be beautifully cared for.

It’s not always so straightforward. There are objects that don’t really have a sure place of origin, a maker or an original owner. Some restitution claims refer to a site of “modern discovery”: where they were dug up, bought or even stolen, rather than where they were created. These artefacts in limbo can present the biggest problems for museum staff facing claims.

Yet despite all the resistance from museums, despite the expense and difficulty, the tears and trouble and wars of words, restitution has been moving at quite a speed in the past few years.

In the US last year an ancient Gilgamesh tablet was returned to Iraq, more than 100 artefacts were returned to Pakistan, and Ethiopia received important pieces looted in the 1860s by British troops. These pieces and many like them were retrieved by officials after they were discovered being traded on the lively but often murky market in antiquities, the proceeds of theft, modern-day looting or unscrupulous dealings.

Germany has been behaving well, returning objects to its former colonial territories in present-day Namibia and announcing the return of their Benin bronzes; the Netherlands and Belgium have also made a series of good-hearted moves. And France’s senate in 2020 voted to return 27 important cultural objects to Benin and Senegal.

All this sounds very right and proper and optimistic. But such artefacts, no matter how precious, have a significance well beyond themselves, as Alexander Herman has pointed out in his recent book Restitution: The Return of Cultural Artefacts.

When President Emmanuel Macron of France made his dramatic pronouncement in Burkina Faso in 2017 — a sweeping promise to return all African artworks in French museums that were illegally acquired — there was more than art and antiquities on his mind. He was deploying cultural soft power in some fairly obvious ways. Righting past wrongs, yes. But also using restitution as a way of reasserting his country’s standing francophone Africa, of trumpeting a clean break with the colonial past, of forging new economic and diplomatic links on a basis of goodwill. As Herman puts it: “The goal of expanding French spheres of influence is well served by an engagement with African countries around questions of restitution.”

Herman talks about China, too. Often through the market rather than through official repatriation claims, China (and its millionaire elite) has been steadily recovering art and cultural objects taken by foreign invaders and adventurers. The restitution wars also work through other channels, though.

According to Herman, “The impressive new museum in Dakar, Senegal, that now holds restituted material from France? Paid for with €35mn from China . . . And it should be added that the port of Dakar represents an essential deepwater transportation hub at the western tip of the continent.”

What’s more, Chinese president Xi Jinping waded into the Parthenon Marbles debate, firmly siding with the Returner cause when he visited Greece in 2019. A diplomatically astute move, Herman says: not a bad idea to be nice to the Greeks about a cultural issue “when the Chinese-owned port of Piraeus is such a vital linchpin to China’s trade with Europe”.

This particular game of marbles, it seems, has some unwritten rules. Today’s quarrels over pieces of stone or metal can have vivid implications for the future.

Jan Dalley is the FT’s arts editor

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