Harpur came of an old and influential Derbyshire family with estates said to be worth £10,000 a year.
In 1768 he again stood for Derbyshire, in opposition to Godfrey Bagnal Clarke, and was defeated after an expensive contest. In 1774 Georgiana, Duchess of Devonshire, reported to her mother that if Wenman Coke were returned for both Derby and Norfolk, Harpur would hold the seat at Derby till Thomas Coke was of age; but Coke was defeated, and Harpur did not stand again for Parliament.
He died 10 Feb. 1789.
