Mrs. Sarah Siddons, 1785. Although Gainsborough produced about a thousand portraits in oil, the artist typically worked directly on the canvas rather than making preparatory drawings of his sitters. This study, so closely related to the artist?s finished painting of the famous actress, Mrs. Sarah Siddons, is highly unusual. One scholar has hypothesized that because the portrait was not made on commission but conceived for an exhibition in his studio, Gainsborough may have had only a single sitting with the celebrated actress, and knew he would he would have to rely on the drawing as a basis for the finished work.