Brussels (AFP)

The painting hung for decades in a town hall in Brussels passed for a simple copy of a Flemish master.

An expert report finally identified him as an authentic Jordaens, the oldest known version of the "Holy Family" painted at the beginning of the 17th century by this pupil of Rubens.

The "incredible discovery", announced Tuesday, is to be put to the credit of the Royal Institute of Artistic Heritage (Irpa), helped by international experts painters Jacob Jordaens and Antoon Van Dyck.

The painting dates from 1617 or 1618, when Jordaens (1593-1678) was just 25 years old, according to Irpa.

Its authentication, on the occasion of an inventory of cultural goods in the Brussels municipality of Saint-Gilles, was notably enabled by a dendrochronology research, making it possible to precisely date the piece of wood used by the painter and its provenance.

The same tree was used by Van Dyck, another disciple of Rubens, with whom Jordaens "most likely worked" in the workshop of the Antwerp master at the same time, explained art historian Constantine Pion, who contributed to Discovery.

On this painting in red, blue and ocher tones, yellowed by time and which will be restored -, appears the infant Jesus, surrounded by Joseph, Mary and her mother, Sainte-Anne.

A composition that Jordaens will reuse - with variations - in three other paintings kept at the Metropolitan Museum in New York, the Hermitage in Saint Petersburg and the Alte Pinakothek in Munich, Irpa said in a statement.

With this masterpiece found in Belgium, "we have a little the matrix of what he will do later, it will allow us to better understand the successive versions" of the Holy Family, Pierre Dejemeppe told AFP , Heritage expert in Saint-Gilles.

It is in an office of the town hall of the municipality that the Jordaens had been hung since the 1960s, without anyone imagining that it was a major work.

“It was five meters high, and for everyone it was a copy, obviously not an original,” one explained to the city's Culture department.

A monumental building built around 1905 and listed as a heritage site, this Town Hall houses a number of works of art, mostly bequeathed by the painter and collector Léopold Speeckaert at the beginning of the 20th century.

An inventory was only undertaken in 2019.

After its restoration by IRPA specialists, the painting will be exhibited "at the end of 2021" at the Royal Museums of Fine Arts of Belgium, in Brussels.

The institution promises to place it "at the heart of one of the most important collections of Jordaens in the world".

© 2020 AFP