Who was the last Prime Minister of Great Britain that served at the same time as leader of the Liberal Party?

Herbert Henry Asquith was the last British Prime Minister that led the Liberal Party at the same time. Asquith became leader of the Liberal Party in April 1908 after the death of Sir Henry Campbell-Bannerman. He served as Prime Minister from 1908 until 1916, but remained leader of the Liberal Party until 1926. David Lloyd George succeeded Asquith as leader of the Liberal Party in 1926, which was after Lloyd George served as Prime Minister.

In 1916 amid issues from the First World War and conflicts within the wartime government, Asquith was removed as Prime Minister, and was replaced by fellow Liberal David Lloyd George. The weakened Liberal Party was still under the leadership of Asquith until 1926. The Liberals lost in a spectacular manner during the 1918 general election, the Conservatives and newly formed Coalition Liberals gained, leaving the Liberal Party with few seats in Parliament.

The conflict between Asquith and Lloyd George helped to weaken the Liberal Party and kept the party from ever being in contention for leadership again. By the 1920’s the Labour Party increased in popularity, while the Liberals were losing in popularity, allowing for the first Labour Prime Minister, Ramsey MacDonald to come to power, although at the head of a minority government. Over the years the Liberal Party languished near the bottom during Parliamentary elections. By 1988 the Liberal Party had merged with Social Democrats to form the Liberal Democratic Party.