 He made his first-class debut in 1831 and appeared in seven matches as an unknown handedness batsman whose bowling style is unknown, playing for Cambridge University.He scored 59 runs with a highest score of 11 and took four wickets.Thornhill was the eldest son of George Thornhill (1783–1852), a Huntingdonshire landowner who became Member of Parliament for Huntingdonshire from 1837 to his death in 1852.