Museums shouldn’t be sending any treasures back, insists this forthright study.

In October 1860, during the Second Opium War, British and French forces attacked the Summer Palace near what was then Peking. Built of jade and marble and filled with treasures crafted exclusively for the imperial family, it had been described as a “dazzling cavern of human fantasy”. Three days of looting left it a smoking ruin. Eyewitnesses told of soldiers carrying off strings of pearls and pencil cases set with diamonds. The empress’s pekinese was also taken and, tactlessly renamed “Looty”, presented to Queen Victoria. Much of the plunder, which the present Chinese government reckons to have totalled 1.5m artefacts, found its way, via salesrooms, into European and American museums, including the V&A, which has one of the richest Chinese collections in the West.

Tiffany Jenkins cites the sacking of the palace as an example of why museums have fallen into disrepute in recent decades, and been seen as shameful relics of imperialism. Her book is a counterblast to such misgivings. It is an outstanding achievement, clear-headed, wide-ranging and incisive. It is also alarming, for her research uncovers a widespread belief among museum curators and cultural officials that museums should dismember themselves and return their holdings, even if legally acquired, to their places of origin.

At its most extreme the case for repatriation can sound like the ravings of some weird apocalyptic sect. In 2002, for example, Turkey’s minister of culture, Ertugrul Gunay, declared: “I wholeheartedly believe that each and every antiquity in any part of the world should eventually go back to its homeland.”

Jenkins’s argument is that, no matter how their collections were acquired, museums are vital to civilisation because they generate knowledge and understanding. Among her heroes is the British archaeologist Austen Henry Layard, who excavated Nimrud and Nineveh, and inaugurated the study of ancient Assyria, sending back the great winged bull and thousands of clay tablets covered in cuneiform script to the British Museum.

Another of Jenkins’s prime exhibits is the Rosetta Stone, an inscribed slab dating from 196BC, which was being used as building material when a soldier of Napoleon’s invading army came across it in the Nile delta in 1799. After Napoleon’s defeat it went to the British Museum and has been on display there ever since. By 1822, researchers had deciphered its inscriptions and solved the lost secret of how to read hieroglyphs, which was the start of Egyptology as an academic discipline.

Egypt has been demanding the stone’s return since 2003, when the head of the Supreme Council of Antiquities called it “the icon of our Egyptian identity”. In fact, Jenkins counters, it is no such thing. The stone belongs to a culture that flourished hundreds of years before the modern Egyptian state was even thought of.

Similar, and for Jenkins similarly spurious, claims are made about the Elgin marbles. In the 1980s the Greek minister of culture, Melina Mercouri, asserted that the Parthenon and its sculptures embody the values of democracy and belong exclusively to the Greek people. On the contrary, Jenkins retorts, the Parthenon was not built by Greece but by the city state of Athens to display its power, and far from being a symbol of democracy it was built by slave labour.

The Earl of Elgin did not steal the sculptures but removed them legally, with the permission of the Ottoman ruler of Greece. The Ottomans had used the Parthenon as an ammunition store, and an explosion had left it a ruin. By the time Elgin arrived in 1801, the Greek people, whose national identity is now supposed to be intimately linked to the Parthenon, were using it as a quarry, busily carting away stone blocks for housing and pounding down sculptures to convert them into mortar.

The Greek government wants the sculptures returned to a special museum it has built for them on the Acropolis, arguing that they can be properly appreciated only on Greek soil. Jenkins’s response is that the British Museum puts them in a global setting, so that visitors can see how the civilisations of Egypt, Assyria and Persia contributed to the achievement of 5th-century Athens. She regards the present situation, with half the surviving marbles in Athens and half in London, as a good solution. It means that they can be seen close to where they were created and also, in London, in the context of other cultures from the past.

Who owns cultural objects is a complex issue, even when their original seizure was clearly unjust. In 1897, a British military force ransacked the royal palace of the Edo kingdom of Benin (now southern Nigeria) and carried off more than 2,000 metal plaques, known as the Benin Bronzes, some dating from the 14th century. The British Museum acquired 700; others were sold to museums across the globe. Understandably Nigeria wants them back.

But, Jenkins points out, the glory of Benin was built on the slave trade, and the Bronzes were crafted from brass bracelets, known as manillas, brought over by the Portuguese and exchanged for slaves whom the Edo captured in neighbouring lands. Do the slaves’ descendants have any right to the Bronzes that cost them their freedom? The creators of the Bronzes might have intended them for the royal house, or for the gods. What is certain is that they did not intend them for modern Nigeria.

Jenkins deplores the relatively recent fashion for museums dedicated to ethnic groups, such as particular Native American tribes, which restrict entry to members of that group and sometimes, if the holdings are considered sacred, to males. That national museums should send items to such museums is, as she sees it, a betrayal of the enlightenment ideal of universal knowledge. Her book is timely. The enemies of enlightenment are strong. In March 2015, Isis bulldozed Nimrud; in September they destroyed parts of Palmyra. That the great national museums should safeguard their collections has never seemed more vital.

OUP £25 pp368

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Some museums have agreed to requests to return artefacts. In 2012 the German government returned the Bogazkoy Sphinx, dated to 1600BC, to Turkey, and in 2011 New York’s Metropolitan Museum handed back to Egypt several relics from Tutankhamun’s tomb.