Arthur Henderson was a British iron moulder and Labour politician. He was the first Labour cabinet minister, won the Nobel Peace Prize in 1934 and, uniquely, served three separate terms as Leader of the Labour Party in three different decades. He was popular among his colleagues, who called him "Uncle Arthur" in acknowledgement of his integrity, his devotion to the cause and his imperturbability. He was a transitional figure whose policies were, at first, close to those of the Liberal Party. The trades unions rejected his emphasis on arbitration and conciliation, and thwarted his goal of unifying the Labour Party and the trade unions.

James Ramsay MacDonald was a British statesman and politician who served as Prime Minister of the United Kingdom, the first who belonged to the Labour Party, leading minority Labour governments for nine months in 1924 and again between 1929 and 1931. From 1931 to 1935, he headed a National Government dominated by the Conservative Party and supported by only a few Labour members. MacDonald was expelled from the Labour Party as a result.