Cavendish was the son of Lord George Augustus Cavendish (1754-1834), the 3rd son of the 4th duke of Devonshire, who had sat for Peterborough, 1775-80, Derby, 1780-Dec. 1796, and Derbyshire, 12 Jan. 1797-10 Sept. 1831. The parliamentary careers of Cavendish’s elder brothers, William (1783-1812) and George Henry Compton (1784-1809), were cut short by untimely deaths and he filled the vacancy at Derby caused by the former’s decease, soon to be joined at Parliament by his younger brother Charles Compton (1793-1863).
Despite his length of service, Cavendish was not a dutiful MP, in part because his military career often required him to be abroad, and in 1832 he was returned in his absence from the nomination, at which the show of hands for him was ‘very small’.
At the 1835 election his cousin, the 6th duke of Devonshire noted that ‘his conduct [had] made it impossible to expect anything but a defeat if he should attempt to stand for Derby’.
