Kay not only painted a number of black profiles but also worked as a miniaturist (he is listed by Long and by Foskett) and as an engraver. Foskett refers to a book by Kay, Series of Original Portraits and Caricature Etchings (1837-38), which contains biographical information, and mentions a self-portrait by Kay, in oils, in the Scottish National Portrait Gallery. For more information on the artist see Robert Brydall, Art in Scotland (Edinburgh and London, 1889), the Dictionary of National Biography and R.T. Skinner, The Royal Mile (Edinburgh and London, 3rd rev. ed. 1994)