A British Trades Union, formerly known as The Miners’ Federation of Great Britain but changed its name to the National Union of Mineworkers ( or NUM) on the nationalisation of the British Coal Industry in 1945.
Its membership streadily declined in the following years from 533,000 to under 250,000 by the early 1980's. This did not prevent the Union from continuing the mineworkers reputation for being the most militant around and famously implemented an overtime ban in 1973 that lead to the three day week and got the credit for bringing down the British Conservative government.
Under the leadership of Arthur Scargill they tried much the same trick in 1984 but failed.
The Nottinghamshire miners and many others refused to strike and formed their own Union of Democratic Mineworkers; the government had ensured there was sufficient coal stocks on hand to keep the power stations going and in May 1985 the strike was abandoned.
The NUM now has a membership of less than 5,000 and falling as the last of the British Coal Industry fades away.