Complex sentence: These were not national parties but local or provincial groups using the Labour Party or Independent Labour Party name and usually backed by local Labour Councils (made up of all the union locals in a city) or individual trade unions.
Split into simpler sentences: These were not national parties, but local or provincial groups using the Labour Party or Independent Labour Party name. These groups were usually backed by local Labour Councils (made up of all the union locals in a city) or individual trade unions.