The Da Vinci feud: has the National Gallery snubbed a Leonardo masterpiece?

It is set to be one of the finest Leonardo da Vinci exhibitions ever staged. But the organisers of the blockbuster show which opens at the National Gallery in London tomorrow have been as assiduous at excluding certain works as they have been at including them, leaked correspondence reveals.

Letters and emails seen by The Independent show how the gallery's director, Dr Nicholas Penny, unceremoniously severed communications with the Canadian owner of La Bella Principessa, a controversial work which made headlines around the world in September after evidence emerged that it was a genuine, £100m Leonardo, not a fake, as previously believed.

The owner, Peter Silverman, and a swath of art experts, insist it is genuine and should be included in the exhibition, titled Leonardo da Vinci: Painter at the Court of Milan. In one email to Dr Penny, Mr Silverman wrote: "I am rather dumbfounded by your silence, indifference and lack of support on this Leonardo thing."

The row eventually became so fierce that Mr Silverman instructed lawyers to act as an intermediary between him and Dr Penny. In a letter dated 19 September, the exasperated gallery director told him: "I do not think there is going to be anything to be gained from further correspondence on this point," calling time on a debate that has lasted for more than three years.

Mr Silverman said yesterday: "It's a great shame that this beautiful teenager, who died so young, has to die a second death at the altar of bruised egos and political expediency." The drawing is believed to show Bianca Sforza, the illegitimate daughter of Leonardo's patron, Ludovico, the Duke of Milan.

According to the National Gallery, the new show concentrates on Leonardo's time in Milan as a court painter working for Sforza.

Despite its owner's protestations, La Bella Principessa has a chequered history. The portrait was sold by Christie's in New York in 1998, catalogued as "German, early 19th century", for £12,039. It was bought by Mr Silverman, a Canadian-born connoisseur, in 2007.

The latest evidence about the work emerged in September. Martin Kemp, emeritus professor of art history at Oxford University, announced that he had identified the drawing as a missing sheet from a 15th-century tome linked to Sforza. "Assertions that it is a forgery, a pastiche, or a copy of a lost Leonardo are all effectively eliminated," he said at the time. A National Gallery spokeswoman said yesterday: "La Bella Principessa is not included in the National Gallery exhibition because there is no general agreement that it is by Leonardo."

In 2008, Dr Penny told Mr Silverman he was "deeply suspicious" of the drawing, although admitted he had not seen it in person. The exhibition includes Salvator Mundi, a work recently identified as a genuine Leonardo by experts including Professor Kemp.

REAL OR NOT REAL?

DISPUTED WORKS

Portrait of a Gentleman by Diego Velázquez

Previously thought to be worth about £300, it was later identified as a Velázquez and is expected to fetch up to £3m at auction.

Missing pieces of San Marco altar piece, by Fra Angelico

Two small panels depicting saintly figures had languished in a pensioner's spare room. Attributed to the Renaissance master, they sold in 2007 for £1.7m.

Madonna of the Pinks by Raphael

Identified as genuine by Dr Penny in 1991, it was later bought by the National Gallery for £34.8m. It was previously believed to be a copy.