Experts have determined that a painting long-believed to have been painted by a student of Rembrandt is in fact a self portrait by the Dutch master, vastly increasing its value to more than $30 million.

The painting, donated to the British National Trust by the estate of an English aristocrat in 2010, has hung since then in Buckland Abbey, a national museum that was once the home of Sir Francis Drake, the famous privateer.

Experts have studied the painting for nearly 50 years, and had long believed that it was made "in the style" of Rembrandt, and likely painted by an apprentice of the seventeenth-century master famed for works like "The Night Watch."

"Our team last scrutinized this self portrait in 1968, and according to what we knew then of Rembrandt's style we decided it was most likely painted by one of his pupils," Ernst van de Wetering, an art historian and chairman of the Rembrandt Research Project said in a National Trust statement.

"But, over the past 45 years we have gathered far more knowledge about Rembrandt's self-portraits and the fluctuations in his style… This analysis and newly found circumstantial evidence remarkably increased the likelihood that the painting was by Rembrandt himself," he said.

Rembrandt was a renowned portraitist, most famous perhaps for portraits of himself.

The painting depicts the artist wearing a puffy blue hat adorned with a large white feather. It is signed "Rembrandt" and dated 1635.

Rembrandt would have been 29 when the portrait was made.

In 2009, a Rembrandt sold at auction for a record breaking $43 million.