Who was the first and so far only British Prime Minister to have served under three monarchs?

Stanley Baldwin, 1st Earl Baldwin of Bewdley (3 August 1867 – 14 December 1947) was a British statesman of the Conservative Party who dominated the government in his country between the world wars. Three times Prime Minister, he is the only British prime minister to have served under three monarchs (George V, Edward VIII and George VI).

Baldwin first entered the House of Commons in 1908 as the Member of Parliament for Bewdley, succeeding his father Alfred Baldwin. He held government office in the coalition ministry of David Lloyd George. In 1922, Baldwin was one of the prime movers in the withdrawal of Conservative support from Lloyd George; he subsequently became Chancellor of the Exchequer in Bonar Law's Conservative ministry. Upon Bonar Law's resignation due to health reasons in May 1923, Baldwin became Prime Minister and Leader of the Conservative Party.

His first term as Prime Minister was 22 May 1923 – 22 January 1924. His second term was 4 November 1924 – 4 June 1929. Both of these terms George V was the monarch. During his third and final term 7 June 1935 – 28 May 1937 he saw three different monarch's during his service, George V (who died), Edward VIII (who abdicated due to his love of the divorced Wallis Simpson) and George VI.