Addison rentered parliament as a Liberal in 1910 after a distinguished medical career. He became prominent over the 1911 National Insurance Act, which began his long association with Lloyd George, He joined Lloyd George at Munitions in Kay 1915. Here he was much involved with manoeuvres that led to his chief becoming prime minister in December 1916. Addison now became Minister of Munitions, and, after many difficulties with labour, Minister of Reconstruction in July 1917 where he planned post-war social programmes. After the 'coupon election', he became in June 1919 the first Minister of Health. His main preoccupation here was building more houses, with state subsidies. This ran into many problems and Addison finally became Minister without Portfolio in April 1921. He quarrelled fatally with Lloyd George over social policy and resided over cuts in housing in July 1921. He lost his seat in 1922, But he now joined Labour, became involved in devising policies for agriculture, and was elected again in 1929. He became junior minister and in June 1930 Minister for Agriculture, Here, he drafted important legislation on marketing boards. In August 1931 he was amongst the Cabinet ministers to oppose MacDonald; he then lost his seat in parliament again. In opposition, he was very active both concermin agriculture and also foreign policy. He was briefly in parliament again and took a peerage in 1937. He later led the Labour peers. In August 1945 he became leader of the Lords and Dominions Secretary. He was also a major figure in Cabinet committees. He led the Lords with reat skill, including during the crisis over steel nationalization. He served throughout the Attlee government and died ii. December 1951. He was a consistent radical, a vigorous minister, a key figure in major political crises, and a notable progressive.