David Glasser, chairman of the Ben Uri Gallery: The London Jewish Museum of Art, saw the Russian-born artist’s gouache, Apocalypse en Lilas, Capriccio (1945-47), at a Paris auction house in October.
Glasser said the previously unknown work was “Chagall’s deeply personal expression of horror and mourning for the Jewish civilisation almost wiped out by the Nazis alongside and merged with grief for his late wife Bella who died eight months earlier.”
The gallery paid about £27,000 for the piece, but announced the acquisition only last month for fear of alerting French officials, who could have intervened and subsequently blocked the export of the work.
But Jean-Paul Mercier-Baudrier, of the French culture ministry, said specialists at the Centre Pompidou in Paris approved an export certificate for the work on 29 October, stating that it “was not an object of national interest”.
Tim Knox, director of the Sir John Soane’s Museum in London and a member of the 2008-09 reviewing committee on the export of works of art, said: “I don’t think the Ben Uri Gallery had a moral duty to point this work out to the authorities.
"French collections are groaning with Chagall’s work, so I can’t imagine that this one would have made a difference. The work is appropriate for the Ben Uri on the grounds of the subject, but it is not the masterpiece that it is being trumpeted as.”
Glasser responded: "There are no doubts here. Ben Uri acted wholly appropriately in full accordance with our own acquisition and disposals policy and the detailed guidance incorporated in the Museums Association Code of Ethics throughout.
"There is no formal or reciprocal or moral obligation for a British museum to publicise and inform the culture ministry of a foreign country of its purchases outside the standard application procedures for export licences.
"Scholars take a different view to Tim regarding the importance and context of the work both within the cannon of Chagall's oeuvre and that of Second World War art. We see this acquisition as a triumph for scholarship and a triumph for British museums and is the first Crucifixion by Chagall in a British public collection."
Although the Art Fund offered the gallery up to £100,000 to help buy the Chagall, Glasser was able to purchase the piece without its assistance, thanks to money provided by a benefactor.
The picture, which is reportedly insured for £400,000, was on view last month in an exhibition to kick-start the gallery’s search for a new 1,800 sq metres building in the heart of central London.