The epochs of the Running of Freight, (I understand them) were:
Regions, LMR, WR, ScR, SR, ER.
Sectors, Railfreight (InterCity, LSE then NSE, Provincial, Parcels)
Within Railfreight it was then split into areas in the late Railfreight early Trainload Freight era. to give:
East Midlands Freight
West Midlands Freight
Yorkshire Freight
Humberside Freight?
West Of England Freight.....
Presumably there were others that covered the whole of the UK?
It was then in the early 1990s that the Trainload Freight reformed and carved up to into three regional companies,
TLF-W, TLF-SE and TLF-NE,
These were what were then rebranded as Loadhaul, Transrail and Mainline. Only to all be sold to what became EWS.