Clement Attlee moved from legal training toward social work and Labour politics through experience in London's East End. Afterward he became mayor of Stepney and entered Parliament for Limehouse in 1922. Ministerial work in Labour governments gave him practical experience, and the party's collapse in 1931 elevated his importance within a much reduced parliamentary group. He became Labour leader in 1935, building authority through reliability, collective decision-making and the management of colleagues rather than flamboyant public performance.

In 1940 Attlee brought Labour into Winston Churchill's wartime coalition. As deputy prime minister from 1942 he handled domestic and cabinet business while Churchill concentrated on military strategy and international affairs. The partnership helped maintain political cohesion during the war. Labour's decisive victory in the 1945 general election then made Attlee prime minister, with a mandate for reconstruction and social reform. His administration faced wartime debts, shortages and severe limits on Britain's economic resources.

The government expanded national insurance and social assistance and established the National Health Service in 1948 under Aneurin Bevan. Major industries, including coal, railways and electricity, passed into public ownership. Housing and education programmes sought to meet longstanding needs, while rationing and austerity continued. Attlee's leadership depended on ministers with strong and sometimes conflicting ambitions. Financial crisis, the devaluation of sterling in 1949 and arguments over health-service charges exposed the pressures on the reform programme. The reforms left class inequality and economic constraints intact.

Foreign policy combined cooperation with the United States, resistance to Soviet influence and the contraction of empire. Attlee and Foreign Secretary Ernest Bevin supported the United Nations, the Marshall Plan and NATO. Britain developed an independent atomic-weapons programme. India and Pakistan became independent in 1947 amid partition and catastrophic communal violence; Burma and Ceylon followed. Decisions in Palestine and other imperial territories also involved conflict and painful legacies. Labour narrowly retained office in 1950 but lost the 1951 election. Attlee remained party leader until 1955 and entered the Lords as Earl Attlee. He died in 1967. He established lasting welfare and public services while managing Britain's reduced global power.