ChiefPlanner
Established Member
GTR set the Any Permittted fare from SAC to London so would not be permitted to introduce a cheaper GTR only fare.
EMT could introduce EMT only fares but this would only increase crowding on the services you'd want people not to use.
At Peterborough it works because LNER sets the Any Permitted therefore GTR can introduce cheaper fares on their slower services.
Milton Keynes is a bit of an exception for day tickets (although not for season tickets) because Virgin historically priced the tickets (allowing Silverlink (as ws) to set up cheaper 'Silverlink only' fares). Silverlink then took over pricing for the Any Permitted fares allowing Virgin to introduce Virgin Only fares but Silverlink were allowed to keep their operator specific fares as a one-off.
Following huge 1996 timetable battles , where neither North London Railways or West Coast Trains would declare their plans for stopping patterns to the very last moment , due to the ORCATS revenue swings.