This may correspond with one of two entries in the artist's account books: p.149, no.540 - 'Portrait of a Grey Horse - 10 10 0' or no.545 - 'For W. L. Gilmore, Esq. - Portrait of a Grey Horse - 10 10 0' (see Major Guy Paget, The Melton Mowbray of John Ferneley (1782-1860), 1931)