English decorative painter. He was the only British painter of his day successfully to emulate the European formulas for wall and ceiling painting and to challenge on their own ground the many foreign decorative painters then at work in England. His two finest works are the grisaille paintings on the Life of St Paul (1716-19) in the dome of the St Paul's Cathedral, London (he beat Pellegrini and Sebastiano Ricci in the competition for the commission), and the Painted Hall at Greenwich Hospital, on which he worked intermittently from 17708 to 1727. Thornhill was appointed History Painter to George I in 1718 and Serjeant-Painter in 1720, was knighted in 1722, and elected Member of Parliament in the same year. Hogarth was his son-in-law. //