Originally known as the General and Municipal Workers’ Union when established in 1924 as a result of a merger between the Gasworkers’ and General Labourers’ Union, the National Federation of Women Workers, the National Amalgamated Union of Labour and the Municipal Employees’ Association. In 1982 the 'boilermakers' was added in, when it joined with the Amalgamated Society of Boilermakers, Shipwrights, Blacksmiths and Structural Workers and became knowns as the General, Municipal, Boilermakers and Allied Trade Union, or GMB for short.
In 1989 it adopted the initials 'GMB' as its official name and dispensed with the long form completely.
As a union it represents workers in a wide variety of industries ranging from the National Health Service and local government to aerospace, construction, well everything really, due to its past policy of amalgamating with any other union it came across. Examples of various trade unions swallowed up by the GMB over the years are;