It represented engineering staff in the Post Office, mostly working in telecommunications.

[1] The union was founded in 1915 when the Post Office Engineering and Stores Association and the Amalgamated Society of Telephone Employees merged, to form the Post Office Amalgamated Engineering and Stores Association.

[3] In 1925, the Post Office Telegraph Mechanicians' Society joined the union.

[1] In 1985, it merged with the Postal and Telecommunications Group of the Civil and Public Services Association, forming the National Communications Union.

[4] The union sponsored Labour Party candidates in each Parliamentary election from 1966 onwards.