Months of careful analysis has confirmed that a 1635 portrait of a 29-year-old Rembrandt was painted by the man himself, putting to rest more than 50 years of speculation on who was responsible for the work. 

The painting, now valued at about $50 million, is the first work by Rembrandt in the National Trust's collection of 13,500 paintings.  

Analysts have debated whether the painting was done by Rembrandt himself or a student since the 1960s, when expert Horst Gerson and the Rembrandt Research Project determined that some brush strokes in the painting were inconsistent with the artist's style. But Ernst van de Wetering, currently the leading expert on Rembrandt, believed the artist had painted the self-portrait and recommended it be thoroughly examined, saying: 

Although I was pretty certain the painting was a Rembrandt when I saw it in 2013, I wanted to further examine it after cleaning and see the results from the technical analysis as this had never been done before. With all this additional scientific evidence, I am satisfied it is by Rembrandt.

The National Trust explains that the painting "went through a series of investigate analyses to include close visual examination under magnification, infra-red reflectography, x-radiography, raking light photography and pigment and medium analysis." David Taylor, the Trust's paintings and sculptor curator said, "the key element for me has been the cleaning. The varnish was so yellow that it was difficult to see how beautifully the portrait had been painted." 

The painting will be on display at Buckland Abbey starting on June 13.