George IV of the United Kingdom
In June 1820 Mouat-Keith visited Queen Caroline of Brunswick, the Queen consort of King George IV of the United Kingdom. He also had a miniature portrait by the "well-known Jewish miniaturist painter, Solomon Polack, a friend of William Makepeace Thackeray", a Flemish artist of 6, Artillery Lane, Bishopsgate Street, London, which was displayed at the Royal Academy of Arts.