Prime Minister of the United Kingdom century as a convention of the constitution, the position of Leader of the Opposition was given statutory recognition in 1937 by the Ministers of the Crown Act. British Prime Ministers have never been elected directly by the public. A Prime Minister need not be a party leader; David Lloyd George was not a party leader during his service as prime Minister during World War I, and neither was Ramsay MacDonald from 1931 to 1935. Prime Ministers have taken office because they were members of either the Commons or Lords, and either inherited a majority in the Commons or won more
Prime minister and in British colonial territories as they developed self-government. In some places alternative titles such as "premier", "chief minister", "first minister of state", "president of the council" or "chancellor" were adopted, but the essentials of the office were the same. By the late 20th century, the majority of the world's countries had a prime minister or equivalent minister, holding office under either a constitutional monarchy or a ceremonial president. The main exceptions to this system have been the United States and the presidential republics in Latin America modelled on the U.S. system, in which the president directly exercises executive authority.