James ('Jimmy') Henry Thomas, (October 3, 1874 - January 21, 1949) was a British trade unionist and Labour politician.

Thomas was born in Newport, Wales, the illegitimate son of a young unmarried mother. He was raised by his grandmother and began work at twelve years of age, soon starting a career as a railway worker. He entered union politics, becoming an official of the Amalgamated Society of Railway Servants and was also active in the newly formed Labour Party, becoming a councillor for Swindon. Thomas entered Parliament in 1910 representing Derby, replacing Richard Bell. He remained active in his union and was one of the leaders of the railway strike of 1911.

In 1913 he helped organize the National Union of Railwaymen (NUR, now part of the RMT) from the amalgamation of several smaller unions, becoming its general secretary in 1917 and leading the successful rail strike of 1919. He was appointed colonial secretary by the incoming Labour government of 1924 under Ramsay MacDonald.

Before the general strike of 1926 Thomas was asked by the TUC to negotiate with the Conservative government of Stanley Baldwin, but the talks proved abortive and the strike went ahead regardless.

In the second Labour government of 1929 Thomas was made lord privy seal and special minister for employment. He became dominion secretary in 1930 and retained that position in Ramsay MacDonald's controversial 'National' coalition with the Liberals and Conservatives (1931-1935). As a result he was expelled from the Labour party and the NUR. For a brief period in 1931 he also served as Colonial Secretary once more.

Thomas served as Colonial Secretary from 1935 until May 1936, when he was forced to resign from politics. It was revealed that he had been entertained by stock exchange speculators and had dropped heavy hints as to tax changes planned in the budget. For example, while playing golf, he shouted "Tee up!", which was taken as it was intended: a suggestion that the duties on Tea were to rise.

Thomas died in London in 1949.

|- style="text-align: center;" | width="30%" |Preceded by:
The Marquess of Salisbury | width="40%" style="text-align: center;" |Lord Privy Seal
1929–1930 | width="30%" |Succeeded by:
Vernon Hartshorn

|- style="text-align: center;" | width="30%" |Preceded by:
The Lord Passfield | width="40%" style="text-align: center;" |Secretary of State for Dominion Affairs
1930–1935 | width="30%" |Succeeded by:
Malcolm MacDonald

|- style="text-align: center;" | width="30%" |Preceded by:
The Lord Passfield | width="40%" style="text-align: center;" |Colonial Secretary
1931 | width="30%" |Succeeded by:
Sir Philip Cunliffe-Lister

|- style="text-align: center;" | width="30%" |Preceded by:
Malcolm MacDonald | width="40%" style="text-align: center;" |Colonial Secretary
1935–1936 | width="30%" |Succeeded by:
William Ormsby-Gore

Further reading

• J. H. Thomas: A Life for Unity by Gregory Blaxland (1964).