The painting of Swalmius, a minister in the Dutch Reformed Church who may have come to the Netherlands from Portugal in 1612, was for a long time listed as "Portrait of a mayor". Then attributed to Rembrandt, it formed part of the collection of the Duke of Orléans, brother of Louis XIV, housed in the Royal Palace in Paris. After the French Revolution, it passed through the hands of a number of British owners before being bought, for 200,000 francs (€5,000), by the Antwerp museum in 1886.

In 1969, scholar Horst Gerson revised the catalogue of autograph Rembrandt works, reducing the number of confirmed works from 639 to only 419. The Swalmius was one of Gerson's victims: it was attributed to Govert Flinck, a pupil of Rembrandt whose painting of the biblical patriarch Isaac blessing Jacob of 1638 bears a striking resemblance to the portrait of Swalmius. The work was taken down and stored in the depot.

Then in 2006, a businessman offered to pay the cost for a restoration, and a team under independent restoration consultant Marie Postec set about removing the thick layer of yellow varnish that had obscured many original details. The original layers of paint proved to be in excellent condition. More importantly, they were proven in the lab to be definitely from the 17th century.

Once cleaned up, the painting was submitted to the scrutiny of Van de Wetering, chairman of the Rembrandt Research Project. "This is a Rembrandt, I thought to myself excitedly," he said later. "And right away I was ashamed of myself, because a scientist ought not to behave that way." He explained what convinced him: "There is that magic, that short distance in which paint becomes illusion, and illusion seems to be paint."

The Swalmius portrait is one of two genuine Rembrandts in a public collection in Belgium. The other is the "Portrait of Nicolaes Van Bambeek" in the Museum of Fine Arts in Brussels. The Antwerp painting, now rehung, is on permanent view to the public.

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