politician who held numerous offices in the British government under King George III and was the object of widespread suspicion as well as deference because of his reputed clandestine influence at court. It was believed that he in some way controlled the relationship between the king and Lord North, prime minister (1770–82) during the American Revolution.

The son of an army officer, Jenkinson in 1760 became private secretary to the 3rd Earl of Bute, favourite of George III, and in 1763, having been elected to Parliament, was appointed joint secretary of the Treasury. He was leader of the “king's friends” in the House of Commons after the retirement of Bute from active politics. Chosen vice treasurer for Ireland (1773), he became a member of the Privy Council. Later he was master of the Royal Mint (1775–78) and, during the American Revolution, secretary at war (1778–82), in which capacity he carried out Lord North's policies.

Jenkinson's reputation improved during the first prime ministry (from 1783) of the younger William Pitt, to whom he was a valuable adviser. In 1786 he was appointed chancellor of the duchy of Lancaster and president of the Board of Trade. A member of the Cabinet from 1791, he became an invalid about 1801, ceased to attend Cabinet meetings, and by the middle of 1804 had resigned all his offices. He was created Baron Hawkesbury in 1786 and Earl of Liverpool in 1796.