[2] In 1871, Prior succeeded Robert Applegarth as general secretary of the ASC&J.
As Prior was based in Manchester, the union's headquarters was relocated to the northern city.
A large minority of the union's branches refused to accept his election but, with the support of Applegarth, Prior asserted his control.
[4] While general secretary, Prior was regularly elected to the Parliamentary Committee of the Trades Union Congress, serving as its chairman from 1876 until 1879.
In 1881, Prior was appointed as a factory inspector, the first worker to hold the post.