A Seventeenth-century portrait of a Spanish writer thought to have been ‘lost’, has been located at Penrhyn Castle,where it has been hung up for nearly 150 years.

Bartolomé Esteban Murillo’s work, which decorates the walls of the popular tourist attraction, had long been thought to be a copy until an art expert recently visited the venue.

Although Penrhyn Castle was gifted to the National Trust by the family, much of its contents is still owned by the Douglas-Pennant’s who created most of their wealth through developing the local slate industry.

The National Trust had assumed that the artwork was of no great value and as such it had remained unvisited by art experts. 

However, according to a report by The Guardian, a recent visit by distinguished art scholar Benito Navarrete Prieto, who travelled from Seville to north Wales in order to take a closer look at the portrait, confirmed that the masterpiece was that of Murillo’s.

The discovery of a Murillo is said to be a major event for European art as there aren’t many known portraits by the artist and those that do exist are reportedly worth millions.

The painting was found among old masters collected in the mid- to late-19th century by Baron Penrhyn for his neo-gothic pile and depicts Don Diego Ortiz de Zúñiga, who wrote a history of Seville.

The portrait has now been transported from Penrhyn Castle to act as the centrepiece in a major exhibition on the artist at the Frick Collection in New York, before it is transferred again to the National Gallery in London in February.

Xavier Salomon, one of the exhibition’s curators, told The Guardian that he went along with the assumption it was a copy even though his first impression on seeing it was that it was “really good”.

“I thought, ‘People have always said it’s a copy, it’s got to be a copy’. Which is, of course, a mistake art historians should never make.” he explained.

“Benito went to Wales and realised how great the painting was and that everyone had been wrong in calling it a copy. The mistake is just that no one, myself included, bothered to go there, and everyone kept repeating that it was a copy.

“It was hidden in plain sight. It’s not coming out of a location that’s unknown. The house was open to the public.”

Murillo worked primarily in Seville until his death in 1682, aged 64. Among his masterpieces are paintings for the city’s convent of San Francisco and for the church of the Caridad, including Christ Healing the Paralytic at the Pool of Bethesda, now in the National Gallery.