The estate of Queen Elizabeth II is facing legal action from Libya which is seeking the return of the Libyan "Elgin Marbles".
The 2,000-year-old columns in Windsor Great Park were stolen by a British colonel in the 19th century and Libya believes the Crown Estate has a "moral obligation" to return them to the Leptis Magna Unesco World Heritage Site, near Libyan capital Tripoli.
“We say that these were stolen and they should be returned as a matter of moral obligation”, Mohamed Shaban, the lawyer acting for Libya, told the Telegraph.
“British values are about doing the right thing, and I think the right thing would be to return these artefacts.
“We have shown great respect so far, and we have perhaps not had the respect that we deserve. For us, now, nothing is off the table.”
British historian and novelist Paul Cooper in 2018 tweeted a thread on the unusual circumstances behind the columns' appearance in Windsor Great Park.
In short, British officer Colonel Hanmer Warrington visited the Roman ruins of Leptis Magna with artist Augustus Earle in 1816 and decided that he liked the look of the "22 granite columns, 15 marble columns, 10 capitals, 25 pedestals, seven loose slabs, 10 pieces of cornice, five inscribed slabs and various fragments of figure sculpture," Mr Cooper wrote.
Despite local outrage, in 1817 Col Warrington shipped the ornate assemblage back to the UK anticipating a laudatory response from the British government.
To his surprise, neither the British government nor British Museum were impressed and for eight years the columns languished in the British Museum's courtyard.
Eventually, in 1826, the stones were given to King George IV's architect, Jeffry Wyatville, who used them to create a folly in the royal estate of the grounds of Windsor Castle.
The Crown Estate has previously disputed this version of events, suggesting the columns were a gift from a local pasha. However, Libya contests the claim and has asked for evidence to be produced to this effect which it says doesn't exist.
UK unwilling to lose its Elgin Marbles
Libyan officials are seeking a negotiated return of the artefacts but Mr Shaban is willing to petition Unesco or launch legal action which could be fought in the UK or the International Court of Justice.
"Much like the Elgin Marbles, they were taken in the 19th century and moved to Britain - almost at the same time in fact. We say that they were stolen and should be returned," he said.
It is an emotional bone of contention for Greece, and one that often spills into the political arena.
At the start of the 19th century, Britain’s ambassador to the Ottoman Empire, Lord Elgin, removed the ancient sculptures from the Parthenon temple on the Acropolis hill and shipped them to England by sea.
For 200 years, prominent Greeks and national leaders have demanded them back. Mr Johnson’s spokesman has said where the artefacts is a matter for the British Museum and not for the UK government.
While Athens’ Acropolis Museum could house the treasures, the British Museum has been reluctant to support their return because it would mean the end of a major London tourist attraction.