Cotherstone, a bay colt, by Touchstone, out of Emma, was bread by John Bowes of Streatlam Castle, Co. Durham. As a two year old, in 1842, Cotherstone heated in the Nursery Stakes at Newmarket. The following year, 1843, when this picture was painted, was Cotherstone's annus mirabilis. After winning the Riddlesworth Stakes, the Column Stakes and the 2,000 Guineas at Newmarket, he went on to win the Derby. He then won the Gratwick Stakes at Goodwood and the Royal Stakes at Newmarket. He only lost the St Leger by a head. At the end of 1843 Cotherstone was bought by the 3rd Earl Spencer for 3,000 guineas. In the following season the horse broke down at Goodwood and never raced again.
The initial 'B' on the rug in the foreground confirms that the picture was painted for John Bowes while he still owned Cotherstone. The picture was presumably acquired by Lord Spencer at the time he bought the horse.