Collectors of British sporting art have a unique chance to purchase George Stubbs’s masterpiece, Brood Mares and Foals, which is to be sold for the first time since it was created in 1767.

The painting, considered the noblest of the ‘Mares and Foals’ series, was produced at a time when the role of the horse was reaching new heights through the development of racing and Thoroughbred breeding; it is thought to have been commissioned by Col George Lane Parker, second son of the 2nd Earl of Macclesfield of Shirburn Castle, Oxfordshire, and one of Stubbs’s most important patrons.

The work passed to the 3rd Earl, whose descendant now offers it for sale by Sotheby’s on December 8 with an estimate of £10 million-£15 million. ‘George Stubbs is, in my opinion, the greatest horse painter ever,’ says Sotheby’s head of British pictures, Emmeline Hallmark. ‘This example is not only in superb condition, but also has the most impeccable provenance.

It is quite simply perfection.’ Stubbs’s auction record is the £3,191,500 paid in 1995 for Portrait of the Royal Tiger; in 1976, Mares and Foals in a Hilly Landscape made £170,000.