This image is based on a miniature by Richard Cosway. Presumably painted some time in the 1780s, it makes a hilarious contrast to the heroic pretty-boy of Reynolds' painting. Which is a better representation of Tarleton's real appearance? Who knows.

A lithoprint with signature, it is presumably of 19th century origin though its original printing is unknown to me. It looks as though it should be part of the Frank Moore set, but does not appear in Diary of the American Revolution. The faint writing around the edge reads: "Delin. by H. B. Hall from a Picture by R. Cosway, R. A." The Cosway miniature itself has been lost.
 
If anyone can supply further information about this image, I'd appreciate receiving it.