The prime minister was not predestined to appear in British history in 1721. The job Walpole came to fill in 1721 had been intermittently done for 750 years by forerunners, called here ‘chief ministers’ for simplicity’s sake. We need to understand the similarities of this earlier post, and how the job of ‘prime minister’ differed. Events from 1688 are critical to understanding why the job appeared in 1721. Walpole’s long period in office embedded the new post, but a certain fuzziness and contingency continued for four decades after he ceased to be prime minister. Only with the arrival of William Pitt the Younger (14th, 1783–1801, 1804–6) did the office of prime minister become a secure fixture in British politics.