The painting at the centre of the dispute. Sotheby’s remain confident of their attribution of ‘The Card Sharps’ to a follower of Caravaggio rather than to the artist himself. It sold at Sotheby’s Olympia in December 2006 for £42,000.

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The version of The Card Sharps offered at Sotheby's Olympia in December 2006 was estimated at £20,000-30,000 and sold for £42,000 to the late collector and art historian Sir Denis Mahon, who died aged 100 in 2011.

In 2007, Sir Denis identified the picture as an original Caravaggio and acquired an export licence, which valued it at £10m, to allow it to be shown at an exhibition in Italy.

The High Court claim, filed at the end of last month, has been made by the vendor at the Olympia sale, Lancelot William Thwaytes, a descendant of Surgeon Captain W. G. Thwaytes, who had acquired Caravaggio's original of The Musicians in 1947 which he sold to the Metropolitan Museum in New York in 1952.

The claim states that the auctioneers "failed to carry out appropriate research" and seeks unspecified damages relating to the price difference between the hammer price of £42,000 and "the true open market value of the painting in 2006".

Sotheby's, however, are confident that their cataloguing was correct and have issued a statement saying they remain of the view that "the painting is a copy and not an autograph work by Caravaggio".

While the Thwaytes claim lists a number of art historians who have lent their support to Sir Denis Mahon's attribution - they include Antonio Paolucci, the director of the Vatican Museums - Sotheby's maintain that their view "is supported by the eminent Caravaggio scholar Professor Richard Spear, as well as by several other leading experts in the field".

News of the claim came at the same time as it emerged that Sir Denis had left his extensive collection of Old Master paintings to the nation on condition that they must remain free to view and never be sold. However, the bequest does not include the painting subject to this High Court action.