To the National Gallery, the man depicted in the masterpiece that hangs in its gallery of 15th-century treasures is a holy man, possibly a saint, reading a legal text. And the portrait is believed – at least by the gallery’s experts – to have been created in the workshop of the Netherlandish painter Rogier van der Weyden.

But to one leading art historian, it is nothing of the sort. Instead, it is a 20th-century fake, of an unknown man sporting a Beatles-style haircut and reading a paper containing nothing more than nonsense.

And, claims Christopher Wright, an old-masters scholar, its likely creator is Eric Hebborn, the greatest forger of modern times. Wright is challenging the attribution of A Man Reading, possibly Saint Ivo, which the gallery label dates to “about 1450”. 

He told the Observer that the picture “screams” the 1960s, and that Hebborn had repeatedly claimed authorship – before denying it.