TAXPAYERS will face a 1.5 billion bill if nine Leonardo da Vinci paintings are damaged or stolen during their time at the National Gallery. It will be among the most extraordinary assemblies of art ever seen in Britain: nine Leonardo da Vinci paintings being exhibited together for the first time. Now it has an equally extraordinary price tag: 1.5 billion. The sum represents the total amount the taxpayer could have to pay if the works are stolen or damaged during their time in the National Gallery, which formally unveils them this week. Shielded with the highest level of security, each of Leonardo da Vincis paintings will be hung behind specially reinforced glass cases to provide maximum protection from theft or accident-prone visitors. But the gallery has had to virtually double the indemnity - effectively the amount it is insured for - from 1.7 billion to 3.3 billion. In contrast, the British Library, which will also stage a landmark exhibition next month of priceless royal manuscripts dating back to the 9th century, has received an increase of just 64 million. It will not be the only big figure attached to Leonardo da Vinci: Painter at the Court of Milan which opens this week. The exhibition is set to attract record numbers of visitors, with the Gallery planning late-night openings and a rare opening on New Years Day to cope with demand. A spokesman for the Gallery said: We have sold an unprecedented number of tickets for Leonardo - more than for any previous exhibition in the Gallerys history. Telegraph The show will focus on the artists 18-year career as a court painter in Milan, working for the citys ruler Ludovico Maria Sforza during the 1480s and 1490s. An engineer, inventor and architect, Leonardo is believed to have painted only around 20 known paintings in his lifetime, including the Mona Lisa and The Last Supper. Only 15 survive and the National Gallery will exhibit nine, in the largest ever collection of his works seen together. Eight of the works are on loan from abroad, and the majority have never been seen before in the UK. Most of the paintings are impossible to value because they would be impossible to sell. But one has a value of 126 million - which is itself controversial. The newly identified Leonardo, Christ as Salvator Mundi (The Saviour of the World), depicting Christ with one hand raised in blessing and the other cradling a globe. The painting, which was long since presumed lost or destroyed, was named as a Leonardo in America earlier this year after being attributed for centuries to Boltraffio, a student of Leonardo. It was sold in 1958 for just 45, bought by an anonymous American consortium in 2005, then attributed to the master this year as recent restoration and conservation convinced many scholars it is Leonardos original work, though some art historians remain unconvinced. Critics say that including it in the exhibition dramatically increases its value if it were to be sold, as it gives it the Nationals seal of approval as a Leonardo. Other works include Portrait of a Young Man (The Musician) from the Ambrosian Library, Milan which has never left Italy before, Saint Jerome from the Vatican in Rome and Portrait of Ceciliana Gallerani, (The Lady with an Ermine) from the National Museum in Krakow, Poland. Depicting Sforzas 16-year-old mistress, the paintings is considered one of Leonardos masterpieces and has been acclaimed as the first truly modern portrait. Luke Syson, the exhibitions curator, has described securing so many Leonardos on loan as miraculous after four years of delicate diplomatic wrangling with international museums, convincing them to part with their star attractions. Polish conservators were strongly opposed to the loan of the Portrait of Ceciliana Gallerani and its inclusion in the exhibition was only secured after Ed Vaizey, the culture minister, stepped in to negotiate with his Polish counterpart. A Polish national security adviser later visited the National Gallery ahead of the painting travelling to London to check security arrangements and the Gallery is believed to have made a payment to the Czartoryski Foundation which owns the painting, to secure the loan. Scepticism also surrounds another painting, Virgin and Child (The Madonna Litta), on loan from the State Hermitage museum in St Petersburg. Its attribution has been questioned in recent years, with some Renaissance experts believing it was painted by one of Leonardos pupils in his Milan workshop. In its catalogue entry, Tatiana Kustodieva, a curator at the Hermitage, acknowledges the paintings chequered attributional history. For the first time in history, Leonardos two versions of The Virgin of the Rocks will be exhibited side by side, with the Louvre museum in Paris loaning its version, the first painted by Leonardo circa 1483-1485, to hang alongside the National Gallerys newly restored picture, painted six to seven years later. The show will include more than 60 paintings and drawings, including those by some of Leonardos pupils and greatest collaborators, Giovanni Antonio Boltraffio and Marco dOggiono. The Queen is loaning more than 30 drawings from the Royal Collection, several on public display for the first time. Tim Marlow, an art historian, said: To be able to see these paintings together is a once in a lifetime moment. Leonardo was undisputedly a great visionary and certainly we are unaware, in the history of art and thought, of another human being who seemed to know so much about the world in which he lived. Leonardo da Vinci: Painter at the Court of Milan at the National Gallery, November 9 - February 5, 2012 Sky Arts 1 will broadcast the opening night of the exhibition live into 40 cinemas across the UK on November 8