Fox was educated at Eton, where he was a contemporary of William Pitt, the Elder. He quickly earned a reputation as a reckless gambler and was forced to go abroad to avoid financial embarrassment. This reputation dogged him throughout his life.
Henry Fox’s parliamentary career began in February 1735 when he became M.P. for the borough of Hinden, in Wiltshire. He was a Whig and quickly attached himself to Robert Walpole, becoming surveyor-general of works in 1737. In 1741 he was returned as M.P. for the borough of Windsor, which he represented until 1761. He resigned from office in 1742, with the fall of Walpole, but became Lord of the Treasury in August 1743, in the ministry of Henry Pelham. In May 1746, he was appointed secretary at war; in this post he was responsible for presenting military and naval estimates to the House of Commons. He became a member of the Privy Council in July 1746. He continued as secretary at war after Pelham’s death in 1754, under the leadership of Pelham’s brother, the Duke of Newcasde.
After Fox became leader of the House of Commons and then secretary of state for the Southern Department (the post of home secretary, after 1782) in November 1755, he began to identify more closely with Newcastle. Fox resigned in November 1756, suspecting that Newcastle was going to blame him for the loss of the Mediterranean island of Minorca; but he was soon followed by Newcastle himself. The king asked Fox to form a ministry with Pitt, but the latter declined, whereupon the Duke of Devonshire formed a ministry with the help of Pitt.
In 1757, Fox was persuaded to become paymaster-general, a post that did not include a seat in the cabinet but that allowed him to amass a large fortune. He held this post until the fall of the Grenville ministry in October 1762 and managed to secure its continuance under the ministry of Lord Bute, although in return he had to agree to serve as leader of the House of Commons.
Fox died at Holland House, near Kensington, London, on 1 July 1774.
Although he served in a Whig administration, Fox often joined forces with William Pitt, the Elder, the Tory leader, in attacking government ministers.
To many of his contemporaries, Henry Fox was a political adventurer whose prime interest was building up the family fortune through his use and abuse of political power. Yet most would also concede that he was a formidable debater and an effective politician if not a great orator.
When he married Lady Georgiana Caroline Lennox, the eldest daughter of Charles, second Duke of Richmond, on 2 May 1744, he went abroad without the consent of her parents, who were not reconciled to the marriage for many years.
Lady Caroline became Baroness Holland, of Holland, Lincolnshire, in the British peerage, on 6 May 1762. Fox had four sons, one of whom was the famous and immensely politically active Charles James Fox.