£20m price tag sees Stubbs race to head of Old Masters' field

Equine portrait set to become one of the most expensive British paintings ever sold

In British master George Stubbs's 1765 painting of the legendary English thoroughbred Gimcrack, the artist shows the horse several lengths ahead of its competitors. Now the work is expected to gallop into the record books to become one of the most expensive British paintings ever sold.

The work, Gimcrack on Newmarket Heath is set to fetch more than £20m when it is sold at Christie's in London in July. "Gimcrack was one of the most popular racehorses of the 18th century and was unusually small, but with incredible staying power," said Christie's senior director of British pictures John Stainton.

"He became something of a favourite, winning 28 out of 36 races which he was entered for, which was a remarkable feat."

The sale will make the work one of the most expensive Old Masters ever sold at auction. The current record for an Old Master is held by Flemish artist Sir Peter Paul Rubens, whose The Massacre of the Innocents sold for £50m in July 2002. If the Stubbs raises more than £20m it will make it the sixth most expensive Old Master ever sold, above Rembrandt's Portrait of a Lady Aged 62, which sold at Christie's for £20m in 2000.

"It is of great importance on many levels," said Mr Stainton. "The use of space is daring and unprecedented in British art at the time. It was a wonderfully wide panorama of the scene, and was unusual in that the central focus is shifted to the extreme left of the composition. In both pictorial and compositional senses it is groundbreaking."

Gimcrack's owner Lord Bolingbroke commissioned Stubbs for the work, and the artist travelled in person to Newmarket, choosing to portray Gimcrack twice in the piece. In the background, the horse is seen winning a trial race by some distance. In the foreground, he is shown with trainer and jockey, being rubbed down by a stable boy. When the horse was sold in 1769 to Lord Grosvenor, Stubbs copied the painting for its new owner, and that version now hangs in the Jockey Club Rooms in Newmarket. There are five paintings of Gimcrack in existence, of which this is considered to be the finest.

Stubbs spent his early career as a portrait painter in his native Liverpool and York, before finding fame as a painter of horses. In 1754 the artist spent 18 months in a Lincolnshire farmhouse, where he dissected and drew horses. In 1766, he published a scientific study The Anatomy of a Horse, which added to Stubbs's reputation as the greatest artist-scientist since Leonardo da Vinci.

"The picture is epicentral to its epoch, it is a hugely English subject and could not have been completed anywhere else in the world," said Mr Stainton. "It is equally extraordinary that Stubbs chose to paint a stable boy, and not the horse's aristocratic patron, again making it of immense importance."

It is the painting's third appearance at Christie's. It was sold by Bolingbroke's descendants in 1943 to Walter Hutchinson, founder of the National Gallery of British Sports and Pastimes. It was sold again in 1951 for just £12,600 to the Woolavington Collection, a collection of sporting art formed by the whisky magnate and racehorse owner Lord Woolavington.

"Stubbs, a very British artist, is set to join a small and select group, added Richard Knight, international co-head of Old Master and 19th-century art at Christie's.

Costly British art

The Massacre of the Innocents by Sir Peter Paul Rubens

After hanging in the corridor of an Austrian monastery for more than 20 years, this 17th century piece went for the world record price for an Old Master work of £49,506,648 ($77,230,374), at Sotheby's London in 2002.

Modern Rome - Campo Vaccino by JMW Turner

Turner's depiction of Rome sold last year for £29.7m, making it the third most expensive painting by a Briton, breaking the artist's own record.

Giudecca, La Donna della Salute and San Giorgio by JMW Turner,

Turner also holds the third place with this oil painting of Venice, one of three he created after his trip there in 1840. It went for $35,856,000 (£20,489,143) at Christie's New York in 2006.

Portrait of a Halberdier by Jacobo Pontormo

This 16th century portrait sold for $35,200,000 (£22,313,280) at Christie's New York in 1989.

Portrait of a Halberdier by Rembrandt Harmenszoon van Rijn

Another portrait, considered one of Rembrandt's best, fetched £20,201,250 ($33,210,855) at Christie's King Street in 2009.