The Northumberland Miner's Union was formed in the 1850s, and incorporated workers from all aspects of the coal industry. However technical changes in coal mining led to an increasing number of mechanics being employed in the coal industry. The colliery mechanics wanted wages and conditions comparable to those of mechanics in other industries, such as shipbuilding or engineering. In 1875 the Northumberland Colliery Mechanics Association broke away from the Northumberland Miner's Union to follow its own agenda.
In 1882 the Northumberland Miners' Union, the Northumberland Colliery Enginemen and Firemen, the Northumberland Deputies, and Northumberland Colliery Mechanics Association joined together to form the Northumberland Federation Board of Miners, Deputies and Mechanics.
In 1917 a new Northumberland Mineworkers' Federation was formed through which the Northumberland Colliery Mechanics became affiliated to the Mineworkers' Federation of Great Britain, which negotiated on a national scale.
From February 1917 all coal mines were brought under state control, though not yet nationalised. The Miners' Federation supported the nationalisation of the coal industry, but the pits were returned to private hands in 1920. The union was affiliated with the Labour Party from 1922, the main political objective being to secure the nationalisation of the coal industry.
The economic situation in the coal industry, and in the general economy as a whole, deteriorated through the early 1920s, until, abetted by the return to the gold standard in 1925 which resulted in a fall in demand for coal exports, the coal owners demanded massive wage cuts. The Miners' Federation refused to accept this. The General Strike began on 4 May 1926 and lasted for 9 days. The mineworkers remained on strike for 30 weeks. The depression saw membership of the union decrease, but as the economy began to pick up again from the mid-1930s increased employment in the industry meant an increase too in union membership.
When war broke out in 1939 many mineworkers left the pits to join up and to work in the armament factories on Tyneside. During the war years there was a considerable shortage of manpower in the coal industry. This meant that the mineworkers could more or less state their own terms of employment. Improvements in pay and working conditions took place, including the introduction of a cost of living scale.
On 1 January 1945 the Northumberland Colliery Mechanics Association became part of the National Union of Mineworkers, and formally ceased to exit. The National Union of Mineworkers, Northumberland Mechanics, Group No. 1 Area was made up of the Durham Mechanics and Enginemen, the Yorkshire Winders and Enginemen, and the Northumberland Mechanics.
From 1 January 1947 the newly formed National Coal Board became responsible for the management of the coal industry, and much of the first years of its life was spent in reorganisation. In the following decade increased demand for coal meant that wages and conditions improved and from the mid/late 1950s further technological innovations were introduced, such as the armoured flexible conveyor and the self-advancing support.
This golden age was short-lived however. A fall in the demand for coal from 1957, due to more efficient use of coal in the energy market, increased use of oil, the move to electric and diesel locomotives, and the introduction of nuclear power, led to the closure of high cost pits, starting in Northumberland in 1958 with Scremerston, New Hartley and Haltwhistle. The workshops at Seaton Delaval, Bedlington and Cramlington were run down, output being concentrated at Ashington. Continuing closures meant that the union was busy in consultations with the NCB ensuring the redeployment of men from the closed pits.
The early 1970s were dominated by wage disputes and overtime bans, partly caused by spiralling inflation and increased in the price of oil. The first national coal strike since 1926 lasted through January and February 1972, with a second threatened strike in 1974 toppling the conservative government of the day. However even under the Labour government the coal industry continued to decline, with further pit closures in Northumberland.
The Northumberland Mechanics and the NUM came up against the attempts of the conservative government to control inflation and rationalise the coal industry in the early 1980s, as conflict which resulted in the Miners' Strike of 1983 - 1984. Since that time the decline of the Northumberland coalfield has continued and the power of the NUM and other coalmining unions has been greatly diminished.