Clement Richard Attlee, 1st Earl Attlee, KG, OM, CH, PC, FRS (3 January 1883 – 8 October 1967) was a British Labour politician who served as the Prime Minister of the United Kingdom from 1945 to 1951, and as the Leader of the Labour Party from 1935 to 1955. He was also the first person to hold the office of Deputy Prime Minister, under Winston Churchill in the wartime coalition government, before leading the Labour Party to a landslide election victory over Churchill's Conservative Party in 1945. He was the first Labour Prime Minister to serve a full Parliamentary term, and the first to command a Labour majority in Parliament.
Mayor of Stepney 1919-1920
The Wikipedia page is [1]
here
Gov.uk page here and UK Parliament page here, The National Archives page is here