This painting was probably commissioned to mark the alliance of the two families through marriage in April 1769. The marriage is between Elizabeth Milbanke (left), the daughter of Sir Ralph Milbanke (beside Elizabeth), 5th Baronet of Halnaby, York, to Peniston Lamb, 1st Lord Melbourne (right). Peniston Lamb (1748 - 1828) took his title, Viscount Melbourne, from Melbourne Hall, near Derby. The rocky setting may represent this area. The central figure is probably Elizabeth's elder brother, John Milbanke. This kind of group portrait, popular in 18th-century England, is known as a conversation piece.
Elizabeth Milbanke became a friend of the poet, Lord Byron, who described her as 'the best friend I ever had in my life and the cleverest of women'. William, her second son, became Queen Victoria's first Prime Minister.
The elegance of Stubbs's work reflects his experience as a painter of the outdoors, as well as his profound knowledge of the anatomy of the horse. The figures in his portraits, though small in scale, are observed with equal care.