[Edit] Emergence of Cabinet government

Despite the reluctance to legally recognise the Premiership, ambivalence toward it waned in the 1780s. As noted previously, George III (1760–1820) is known to have attended only two Cabinet meetings. However, during the first twenty years of his reign, he tried to be his own "prime minister" by controlling policy from outside the Cabinet, appointing and dismissing ministers, meeting privately with individual ministers, and giving them instructions. These practices caused confusion and dissension in Cabinet meetings, especially during the dysfunctional ministries of the Earl of Chatham from 1766–1768 and of the Duke of Grafton from 1768-1770 when no one, not even the King, seemed to be in charge.^[41]

After the failure of Lord North's ministry (1770–1782) in March 1782 due to Britain's defeat in the American Revolutionary War and the ensuing vote of no confidence by Parliament, the Marquess of Rockingham reasserted the Prime Minister's control over the Cabinet. Rockingham assumed the Premiership "on the distinct understanding that measures were to be changed as well as men; and that the measures for which the new ministry required the royal consent were the measures which they, while in opposition, had advocated." He and his Cabinet were united in their policies and would stand or fall together; they also refused to accept anyone in the Cabinet who did not agree.^[42] King George threatened to abdicate but in the end reluctantly agreed out of necessity: he had to have a government.

From this time, there was a growing acceptance of the position of Prime Minister and the title was more commonly used, if only unofficially.^[23][43] Associated initially with the Whigs, even the Tories started to accept it. Lord North, for example, who had said the office was "unknown to the constitution", reversed himself in 1783 when he said, "In this country some one man or some body of men like a Cabinet should govern the whole and direct every measure."^[44][45] In 1803, William Pitt the Younger, also a Tory, suggested to a friend that "this person generally called the first minister" was an absolute necessity for a government to function, and expressed his belief that this person should be the minister in charge of the finances.^[34]

The Tories' wholesale conversion started when Pitt was confirmed as Prime Minister in the election of 1784. For the next 17 years until 1801 (and again from 1804 to 1806), Pitt, the Tory, was Prime Minister in the same sense that Walpole, the Whig, had been earlier.

Their conversion was reinforced after 1810. In that year, George III, who had suffered periodically from mental instability (due to a blood disorder now known as porphyria), became permanently insane and spent the remaining 10 years of his life unable to discharge his duties. The Prince Regent was prevented from using the full powers of Kingship. The Regent became King George IV in 1820, but during his 10 year reign was indolent and frivolous. Consequently, for 20 years the throne was virtually vacant and Tory Cabinets led by Tory Prime Ministers filled the void, governing virtually on their own.

The Tories were in power for almost 50 years, except for a short Whig ministry from 1806 to 1807. Lord Liverpool was Prime Minister for 15 years; he and Pitt held the position for 34 years. Under their long, consistent leadership, Cabinet government became a convention of the constitution. Although subtle issues remained to be settled, the Cabinet system of government is essentially the same today as it was in 1830.

Under this form of government, called the Westminster System, the Sovereign is Head of State and titular head of Her Majesty's Government. She selects as her Prime Minister the person who is able to command a working majority in the House of Commons, and invites him to form a government. As the actual Head of Government, the Prime Minister selects his Cabinet, choosing its members from among those in Parliament who agree or generally agree with his intended policies. He then recommends them to the Sovereign who confirms his selections by formally appointing them to their respective offices. Led by the Prime Minister, the Cabinet is collectively responsible for everything the government does. The Sovereign does not confer with its members privately about policy or attend its meetings. With respect to actual governance, the monarch has only three constitutional rights: to be kept informed, to advise, and to warn.^[46] In practice this means that the Sovereign reviews state papers and meets regularly with the Prime Minister, usually weekly, when she may advise and warn him regarding the proposed decisions and actions of Her Government.^[47]