A rollicking painting of peasants dancing in the open air at a boozy wedding immediately caught the eye of the new director of the Holburne Museum in Bath when she first toured the stores of her new kingdom. Her eye was keen: from under layers of grime and discoloured varnish, a previously unrecognised work by the 17th-century Flemish painter Pieter Brueghel the Younger has emerged.

Wedding Dance in the Open Air had previously been catalogued not even as a studio work but as a lowly later copy. It has now been accepted by experts as a genuine work by the master, and will form the centrepiece of an exhibition next year at the museum on the Brueghel dynasty of artists, the first in the UK.

“The more I looked at the panel, the better it seemed,” said Jennifer Scott, who was curator of the Royal Collection before taking over in Bath two years ago. “Even under the grime the detail and the colour seemed fantastic, far too good for a mere copy.

“It helped that I had so recently been working on the Dutch and Flemish paintings in the Royal Collection. He is a wonderful painter, whose reputation has steadily been on the rise – even a few years ago people would have said: ‘Oh, bad luck, the Younger not the Elder,’ but now everyone is genuinely excited to hear of a new discovery of his work.”

The attribution means the museum now has three paintings by the artist, more than in any other UK collection.