 Changes to the groups and numbers of seats were made over time, as the number of workers represented in different industries fluctuated, but the system survived intact until the early 1980s.Most of the members elected from Group 1 represented the large Miners' Federation of Great Britain, or its successor, the National Union of Mineworkers, but there were several smaller unions which often managed to win one seat.Throughout this period, Group 2 comprised three railway unions