the leading trade union in the manufacturing sector of the United Kingdom, created in 1992 through the merger of the Amalgamated Engineering Union (AEU) with the Electrical, Electronic, Telecommunication and Plumbing Union (EETPU).

Of the two organizations, the AEU was larger and older, though both originated as unions of skilled craftsmen and only later opened their ranks to all employees within their respective industries. The AEU's forerunner was the Amalgamated Society of Engineers, a powerful craft union formed in 1851 through a merger with nine other unions. The AEU began to organize on industrial lines in the 1920s as crafts gave way to mass production. Despite a 40 percent membership decline in the 1980s, the AEU remained the second largest union of metalworkers in Europe into the 1990s. Like the AEU, the EETPU was also a product of mergers, having formed in 1968 through the coupling of the Plumbing Trades Union (founded in 1865) with the Electrical Trades Union (founded in 1889).

The merger of the AEU with the EETPU in 1992 created a union of about one million members. The new AEEU was formed to meet the changing needs of British industry in the early 1990s.