Turner's painting of Flint Castle sells for £541,250
A painting of Flint Castle by Joseph Mallord William Turner has sold at auction for £541,250.
The painting, which had a top guide price of £500,000, was sold at Sotheby's in London.
The watercolour sketch over pencil is considered one of Turner's greatest Welsh landscapes, and captures the castle on the Dee Estuary in the 1830s.
It was sold by a private collector who did not want to be identified.
Emmeline Hallmark, director and head of British paintings and watercolours at Sotheby's, said: "We are delighted with the price achieved for this rare and important work by Turner, and it clearly demonstrates the strength of the Turner market."
Turner completed a second watercolour of the castle in 1835, which is owned by the National Museums and Galleries of Wales.
It is displayed at the National Museum Wales in Cardiff for about three months every year.
Flint Castle was completed in 1284 and its four towers still stand.
However, it was largely destroyed some time after 1646, following its fall to parliament during the Civil War.
Other Turner works featuring Welsh landscapes include Dolbadarn Castle, Ewenny Priory and Harlech Castle.
According to Sotheby's, Turner drew two watercolours of the ruin following his first visit to the castle in 1792.
He returned several times, and painted the auctioned landscape in the 1830s.
Sotheby's pre-sale catalogue said the "rays of the sun draw the viewer's eye outwards towards the edge of the image, mirroring the effect of peripheral vision, a device repeated in many of his later watercolours".
The catalogue also said the painting shows the "technical mastery" Turner had displayed by the 1830s, using a "sponge or a cloth to draw out the colour from the paper and create the sun, its rays across the sky and its reflection off the water".