Smith entered Parliament in 1788 as member for St Germans, and was an MP for the next 44 years, also representing Leicester (1790–1818), Midhurst (1818–1820) and Wendover (1820–1832). He and his son Abel were Wendover's last MPs, as they sat together as its members for the last two years before the borough's abolition. In 1826, being the longest continually-serving MP, he became Father of the House. He did not return to Parliament after the 1832 Great Reform Act, dying two years later.
