Walpole always denied that he was "prime minister", and throughout the 18th century parliamentarians and legal scholars continued to deny that any such position was known to the Constitution. George II and George III made strenuous efforts to reclaim the personal power of the monarch, but the increasing complexity and expense of government meant that a minister who could command the loyalty of the Commons was increasingly necessary. The long tenure of the wartime prime minister William Pitt the Younger (1783–1801), combined with the mental illness of George III, consolidated the power of the post. The title was first referred to on government documents during the administration of Benjamin Disraeli but did not appear in the formal British Order of precedence until 1905.
When was the position of prime minister finally formalized?
1905