A 200-year-old painting thought to be a copy has been identified as the original Portrait of a Tyrolese Lady by renowned 18th-century artist Rosalba Carriera.

Carriera was known as the "Queen of Pastel Painting" for painting a series of women from across Italy during the early 1700s and was greatly admired by King George III.

The painting was left by Maurice Egerton, the fourth and last Lord Egerton of Tatton, to the National Trust when he died heirless in 1958.

After being placed in storage in the 1980s at Tatton Park in Cheshire it has now been identified as an original piece upon the discovery of a unique slip of paper tucked behind the frame.

Xavier Salomon, deputy director and chief curator of the Frick Collection in New York, says that the slip of paper was a "Santini."

It features prayers and blessings for a safe passage that the artist hid in works she exported.

"Xavier Solomon is researching Carriera's works and working on a new catalog," said Carolyn Latham, the Mansion and Collections Manager for the National Trust. "He approached us about visiting to study the work as he believed it could be an actual Carriera."

"The picture has been in our picture store since the mid-1980s and was thought to be a copy of a Carriera work rather than by her. Xavier had hoped to find the Santini still tucked into the back and we were all really pleased to find it there," she said.

It's quite extraordinary the rate at which paintings produced by great Renaissance and Enlightenment artists are rediscovered after being mislabeled, lost, or damaged. Those days are long gone, and one would think that pretty soon they would all have been found considering no more are being made. But they keep turning up, like this Van Dyck painting that was covered in bird droppings in a shed.

After extensive restoration, the artwork is now on display at Tatton Park for visitors in the Mansion's Yellow Room until it is closed for winter conservation at the end of October.

"Over time these fragile bits of paper often became lost or separated from her works," said a spokesperson for the Tatton Park estate.

"Rosalba became one of the most popular and sought-after artists. From her beginnings as a painter of scenes for snuff box lids, she moved on to portrait miniatures and then became integral in popularising the use of pastels."

"She was an initiator of the Rococo style and is remembered as one of the most successful women artists of any era, but sometimes her work was considered risqué due to the delicate lace coverings, depicted on the subject's clothing only just saving their modesty."

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