John Robert Clynes (1869-1949) began work in a cotton mill when he was 10 years old. At 16 he wrote a series of articles about child labour in the textile industry and in 1886 he helped form the Piercers' Union. In 1892, Clynes became an organiser for the Lancashire Gasworkers' Union and came in contact with the Fabian Society. He joined the Independent Labour Party and attended the 1900 conference that formed the Labour Representation Committee which became the Labour Party.

Clynes stood for the new party in the 1906 general election and was elected to Parliament becoming one of Labour's bright stars and was elected vice-chairman of the party in 1910. During the First World War Clynes was a supporter of British military involvement and in 1917 became Parliamentary Secretary of the Ministry of Food in the Lloyd George coalition government.

Clynes became leader of the party following the war and led it through its major breakthrough in the 1922 general election when Labour went from 52 seats to 142.

Ramsay MacDonald had resigned as Labour leader in 1914 due to his wartime pacifism and lost his seat in the 1918 general election. MacDonald returned to the House of Commons in 1922. MacDonald's pacifism had been forgiven and when the newly titled position of "Leader of the Labour Party" and "Chairman of the Parliamentary Labour Party" was elected, Clynes was narrowly beaten by MacDonald.

When MacDonald became Prime Minister he made Clynes the party's leader in the Commons until the government was defeated in 1924. In the second MacDonald government of 1929-1931, Clynes served as Home Secretary. In 1931, Clynes sided with Arthur Henderson and George Lansbury against MacDonald's support for austerity measures to deal with the Great Depression and split with MacDonald when he left Labour to form a National Government. Clynes was one of Labour's casualties in the 1931 election, losing his seat, but he returned to the House of Commons in 1935 and remained until his retirement in 1945.

|- style="text-align: center;" | width="30%" |Preceded by:
The Viscount Cecil of Chelwood | width="40%" style="text-align: center;" |Lord Privy Seal
1924 | width="30%" |Succeeded by:
The Marquess of Salisbury

|- style="text-align: center;" | width="30%" |Preceded by:
Sir William Joynson-Hicks | width="40%" style="text-align: center;" |Home Secretary
1929–1931 | width="30%" |Succeeded by:
Sir Herbert Samuel