London based JOHN THOMAS MITCHELL (ca.1773-1844) for over 3 decades a Royal Academy exhibitor was primarily a Portrait Miniaturist of some merit. Between 1808-1818, as evidenced by Academy catalogues and a printed Trade-label, he entered into a studio partnership with Watchmaker and Profilist Joshua Trewinnard (1761-1837) in London's Strand, one of the Capital's prime commercial thoroughfares.
To Be Continued
Source: McKechnie (Author of, British Silhouette Artists and their Work 1760-1860)
Mitchell, John Thomas (McKechnie Section 2)