He became a prominent figure in the artistic life of Scotland, holding a variety of official positions. He exhibited portraits, miniatures, landscapes and genre paintings. On 16 July 1823, his younger brother
Anthony Todd Thomson submitted a request to
Robert Dundas that Thomson succeeds the late
Sir Henry Raeburn as the King's
Limner for Scotland, (the post was given to
David Wilkie). On 17 April 1824, he was elected Associate Member of the Institution for the Encouragement of Fine Arts in Scotland which later became the
Royal Scottish Academy. On 7 October 1829, he was elected academician of
Royal Scottish Academy. In 1831, as trustee to the estate of
Hugh William Williams (Artist) along with Mrs Robina Williams, Aeneas MacBain WS, he organised a studio sale. In June 1832, he painted a miniature of his step niece
Elizabeth Gaskell see below. (née Stevenson) author of Cranford. In 1834 and 1835, he was a director of the Caledonian Insurance company alongside
Henry Raeburn. He lived at 47 Northumberland Street, Edinburgh in the 1830s until he died on 24 March 1845 He is buried at
St John's Episcopal graveyard in Edinburgh. The grave lies on a south-facing wall at the west side of the lower terrace. His wife and children lie with him. The memorial to his parents and grandparents is in
Canongate Churchyard. ==Family==