The Triple Alliance was an alliance of British Trade Unions comprising the Miners Federation of Great Britain, the National Union of Railwaymen and the National Transport Workers' Federation (the latter an association of dockers, seamen, tramwaymen, and road vehicle workers' unions).
Triple Alliance (1914) Wikipedia
After a period of intense industrial unrest beginning in July 1910, the Triple Alliance was formed in early 1914 by the Miners Federation of Great Britain, the newly unified National Union of Railwaymen and the National Transport Workers' Federation. It appeared to signal a significant step towards greater unity and syndicalist ideology within British trade unionism. The onset of the First World War, however, curtailed any imminent action by the Alliance. In his famous book of 1936, The Strange Death of Liberal England, the writer George Dangerfield argued that if war had not broken out, there would have been a devastating General Strike coordinated by the Triple Alliance in October 1914.
There was a cessation of Trade Union activity during the war. The industries represented by the Triple Alliance (mining, the railways and other transport systems) were temporarily nationalised for war service.
The mining industry was privatised on 1 April 1921 and the mine owners immediately threatened wage reductions. The Miners' Federation of Great Britain planned a coordinated response with its allies in the Triple Alliance on Friday the 15th.
Following some confusion over what terms the Miners' Union would be prepared to accept, the transport workers' and railwaymen's unions decided not to call their members out on strike in sympathy with the miners. This was subsequently remembered as 'Black Friday' by many socialists and trade unionists, who regarded the collapse of the Triple Alliance as a betrayal of solidarity and a major defeat for trade unionism.
The Triple Alliance was significant in securing government subsidies for miners' wages on 'Red Friday' in July 1925, threatening a General Strike. The Triple Alliance agreed to back the miners in their dispute against the mine owners who had announced future wage cuts and increasing work hours a month previously, threatening a complete halt to the production and transport of coal.