The new Leonardo da Vinci exhibition at London's National Gallery opens tomorrow, however it has long been regarded as the highpoint of the city's Winter cultural attractions.
Through the gallery's own treasures and those on loan from the likes of the Louvre in Paris and St Petersburg's Hermitage, the show tells the tale of da Vinci's spell in the late 15th century as court painter to one of Renaissance Italy's most powerful men, Lodovico Sforza, the Duke of Milan.
Thanks to the power of the image of Mona Lisa and the imagination of Dan Brown, the da Vinci brand will never lack box office appeal. But, just in case, curators for this new exhibition have used another of the artist's most recognisable works to help drive publicity.
Lady with an Ermine is one of only a handful of Leonardo portraits known to survive. Painted onto a small wooden panel with oils, it depicts Cecilia Gallerani, Sforza's teenage mistress, clutching a stoat. The animal is not thought to have been a random prop but chosen because Leonardo wished to add a further symbol of his subject's purity to please his paymaster. The ermine was believed to rather face death than soil its white winter fur.
Ironically, given the purity to which one of history's most famous polymaths was alluding more than five centuries ago, the painting itself has become one of many symbols of a much darker episode in history, one which stretches back 70 years.
It was one of an estimated 600,000 paintings stolen by Germany during a looting programme instigated by Hitler himself to stock what he intended to be the planet's largest museum in his boyhood home town of Linz.
Through forced sales or confiscations from Jewish collectors, a network of magpie collaborators and agents, and secret trades with renowned state collections anxious to protect their finest pieces, the Nazis acquired one-fifth of the world's fine art treasures.
At least for Lady with an Ermine, the trauma was not to last too long. It had been pulled from its hiding place in an outbuilding at the country home of its owner, the Polish prince Augustin Czartoryski, in December 1939. Just over five years later, it was safely recovered by the Allies from the haul seized from Reichskommissar Hans Frank, the Nazi's officer in charge of Poland, as he tried to flee to safety.
The most famous Leonardo of all was reputed to be among works retrieved in much more dramatic circumstances. While writing our book on the subject of war art loot, myself and Peter Harclerode discovered documents suggesting that 6,500 items, including the Mona Lisa, were down an Austrian salt-mine and only hours from being blown up by retreating Nazis when they were rescued by Allied secret agents.
However, even though the Czartoryskis had Lady with an Ermine returned to them, they are among families still fighting to get back many tens of thousands of other pieces of art stolen just before and during World War Two. Although the wartime owners have died, their heirs have combed archives and libraries as well as arguing in galleries and courtrooms in an attempt to win restitution.
There have been some high-profile successes but, sadly, they are exceptions. Given recent developments in Europe and the United States, any positive momentum looks like being stopped in its tracks even as new initiatives allow access to the sort of paperwork which might support restitution claims.
The US Supreme Court recently decided that California couldn't extend a statute of limitations which might give affected families more time to have missing works handed back to them. Sir Norman Rosenthal, the former leading curator at London's Royal Academy of Art, has called for an end to the restitution process, suggesting that it is not an effective way to erase a painful and destructive chapter in history.
Meanwhile, modern collectors seek to defend their ownership of disputed art by claiming that they had bought pieces in good faith. They include Andrew Lloyd Webber, who was allowed to auction a Picasso for £35 million last year after demands for its return from one Jewish family had halted a previous sale at Christie's auction house in New York.
Despite the potential narrowing of their chances for success and the passage of more than 60 years since the end of the Second World War, the families press on. In Amsterdam, Christine Koenigs is keen to trace more than 2,600 drawings and 46 Old Master paintings which had belonged to her grandfather. Her enquiries also extend to a portrait of van Gogh's physician which once held the title as the most costly work of art ever sold at auction.
Whether her long quest for justice enjoys the same sort of happy ending as those with whom the image of Cecilia Gallerani resides remains to be seen.