The collection of drawings that we have remaining from his career have been dispersed into a huge variety of public and private collections. Many were originally a part of sketchbooks before being pulled out and sold seperately, or gifted to friends and family of the respective owners. This has meant that producing an accurate appraisal of his work in this medium is difficult and time consuming. Their availability online has at least allowed this task to be completed a little quicker, with major British institutions holding a good number of his sketches between them. The likes of the British Museum and the Royal Academy have published photos of these works online, alongside brief, but helpful descriptions about the artworks themselves as well as the routes they took in order to end up where they now reside. There is a good variety of content here too, with caricatures, portraits and animal based themes, as well as different mediums, including pencil, ink, chalk and watercolour.
The sketch that you find shown on this page, with a larger version further down, is of The Honourable Mrs Norton and was produced in a combination of oil, charcoal and crayon. It is in a relatively good condition, compared to many other drawings from his career that still remain.