On 31 March 1921 the coalmines were returned to private ownership. The miners' union refused to accept the owners' new terms, and on 1 April 1921 one million British miners were locked out. The lockout lasted for three months, with the miners returning to work in early July 1921.
A week into the lockout, the Miners' Federation of Great Britain sought support from the other members of the 'Triple Alliance' (which had been formed in 1914). It was anticipated that the National Union of Railwaymen and the National Transport Workers' Federation would call for a national rail and transport strike in support of the miners, however, on 15 April, it was announced that they would not recommend action.
The Triple Alliance fell apart, and this fracturing of support was named 'Black Friday'.
In this pamphlet 'The Lesson of Black Friday' author and journalist Gerald Gould explores the structure and activities of the trade union movement during the 1921 lock-out.