Prime ministers of the United Kingdom (1730–2009)

The title of prime minister has been applied to the highest position in British politics since the first half of the eighteenth century. Sir Robert Walpole is regarded as the first prime minister, by virtue of his standing as the acknowledged leader of the cabinet of king's ministers. This designation was, however, informal. As a result, the start of Walpole's premiership is open to interpretation and is here dated from the resignation of his colleague Charles Townshend, second Viscount Townshend, only after which Walpole gained an unrivalled control of the administration and its policies.

Though a fixture in British government from Walpole, the office of prime minister was not recognized in law until the first decade of the twentieth century, and carried no salary. Most prime ministers actually held the formal office, salary, and London residence (10 Downing Street) of first lord of the treasury; this became the invariable practice in the twentieth century. Since the office of prime minister was, until the twentieth century, informal and unpaid, the exact dates of assuming office (generally taken to be the point at which the minister kissed the sovereign's hands) are not always certain before the second half of the nineteenth century. There also remain differences of interpretation about the precise holders of the position in the eighteenth century: two politicians, William Pulteney, earl of Bath (1684–1764), and James Waldegrave, second Earl Waldegrave (1715–1763), accepted office as first lords of the treasury. Pulteney actually kissed hands (in February 1746) but was unable to form a ministry capable of commanding majorities in the House of Commons and House of Lords, and resigned within days of his appointment. Waldegrave accepted office in July 1757, but did not kiss hands and instead helped form the coalition that returned the duke of Newcastle to office.

No party designations are given for prime ministers before Lord Liverpool. Before this period all prime ministers came from political groupings that either rejected labels or would have described themselves as whig. In the early nineteenth century the political successors of William Pitt the younger came to accept the label ‘tory’, leaving ‘whig’ to their opponents.