One of the world’s leading experts on Rembrandt has asked London’s National Gallery to reconsider a decades-old decision that Old Man in an Armchair (1652) is not by the Dutch master, according to the Guardian. The work was purchased by the National Gallery in 1957.  Twelve years later, experts at the museum decided that it was not by Rembrandt himself but by a so-called follower.

However, after seeing the work three years ago, Ernst van de Wetering, the long time director of the Rembrandt Research Project, became convinced that his colleagues got it very wrong. Not only is Van de Wetering convinced that Old Man in an Armchair is a genuine Rembrandt, but also that it is a pivotal work. “It is of wonderful quality and is revolutionary in a sense,” Ernst van de Wetering told the Guardian. “It is a very important painting.”

He claims that variations in the painting that the National Gallery staff cited in discrediting the work should, in fact, be seen within the context of Rembrandt’s experimentation at the time. He says this period started in 1651, one year before Old Man in an Armchair was created. Van de Wetering is nearly giddy in his excitement about the picture, “This is a man posing to be studied…it is a painting about painting.”

A spokeswoman for the National Gallery was rather more blasé in her comment: “Old Man in an Armchair is a picture that has generated much debate over the years—as many Rembrandts do—and we look forward to further discussions concerning its attribution.”