[2] Bentinck sat as Member of Parliament for Lewes between 1766 and 1768,[2][3] for Carlisle between 1768 and 1774,[2][4] for Nottinghamshire between 1774 and 1796[2][5] and for Clitheroe between 1796 and 1802.
[2][6] The Clitheroe seat was reportedly to be purchased by the Duke of Portland from the Lister family for £4,000.
However, the money could not be found and Thomas Lister was granted a peerage on Portland's recommendation as compensation.
[2] Despite his long parliamentary career Bentinck never held ministerial office.
Bentinck married Elizabeth, daughter of the dramatist Richard Cumberland, on 28 December 1782.