William Henry Mainwaring (1884 – 18 May 1971) was a Welsh coal miner, lecturer and trade unionist, who became a long-serving Labour Party Member of Parliament. Both as a trade unionist and a politician he struggled, largely successfully to counter Communist influence. He was said to have spoken "with passion and fire on behalf of his fellow miners". Mining Mainwaring was born in Swansea and went to local schools, leaving to work as miner in the South Wales coalfield. He was a member of the South Wales Miners' Federation, and through their sponsorship was able to continue his education at the Central Labour College in London where he studied economics. Labour College lecturer After two years at the college, he returned to the coal face, but in 1919, Mainwaring was appointed as a lecturer in Economics and Vice-Principal of the Central Labour College. This college, which renamed as The Labour College in 1920, was founded by the South Wales Miners' Federation and the National Union of Railwaymen, but most of the students were South Wales miners; opponents suspected the college was "class teaching for revolutionary aims". Miners' agent Mainwaring ran for the South Wales nomination for a candidate to be Secretary of the Miners Federation of Great Britain in 1924, but was narrowly defeated by A. J. Cook. Mainwaring polled 49,617 against Cook's 50,123 votes. Cook went on to win the post and vacated his previous post as miners' agent for the Rhondda district; Mainwaring was appointed to succeed him. He was one of two agents for the district, and with his fellow agent Alderman David Lewis, Mainwaring had to fight the attempts by members of the Communist Party of Great Britain to gain influence. In 1928, under Communist influence, the lodges of the Rhondda Miners' Federation called for a membership ballot to elect their representative on the South Wales Miners' Federation executive. Mainwaring and Lewis offered their resignations but the district committee refused to accept them. Industrial dispute After a new law allowed the miners' working day to increase to 7½ hours, the South Wales coalowners decided to reduce the wages of miners in November 1930. Mainwaring declared that the new terms of employment were "absolutely preposterous" and threatened to lead a strike. However, after lengthy negotiations, the South Wales miners agreed to work under the new terms "under protest". Communists picketed the Lewis Merthyr colliery at Trehafod in