It represented lower-paid staff within the British Civil Service such as cleaners and messengers.
[2][3] The union primarily represented staff who worked in the Civil Service, but also in other public organisations.
The CSU was seen as being more militant than other unions within the civil service and was, along with the Civil and Public Services Association, the first to adopt a strike policy backed by a fighting fund, in 1969.
[4] The CSU also supported introducing a closed shop policy within the civil service.
[5] By the late 1970s the CSU had 46,827 members, of whom 45,732 worked in the civil service.