With increased frequencies, the GWR will have almost a turn up and go service on the main routes. One must therefore question why turn up & go passengers must pay such high fares compared to those who pre-book in Advance for specific trains? OK, I know what you are thinking - they must have cheaper advance fares so as to spread the loadings.
Let us suppose that someone pre-books an advance fare (11 weeks ahead) from Heathrow (via bus link to Reading) for some place out west - such as Bath or Cardiff. They are not sure when they will clear immigration and reach Reading so they play safe and pre-book a train for say 11am having landed at 8am. By good fortune, they arrive at Reading at 9.50am and then have to sit and wait while trains depart - with empty seats, for their destination as they must wait for the 11am train. Such passengers - who could be on their way, then 'clutter up’ stations. I have used Reading as an example because it caters for lots of Heathrow passengers, however, the same unfriendly user system exists for people who have a business meeting in say London and arrive at Paddington early enough to catch a non pre-booked train only to end up hanging around. This is surely not in the best interests of the TOC & certainly not the travelling public.
What I would like to see (for all rail travel) is a system where we have 3 price levels - peak, cheap and shoulder. Each train would be priced according to normal predictive demand and marked as such on the timetables. Some journeys - such as those in the middle of the day, could be really cheap and may even attract the Megabus crowd. Where a passenger is on a train on a journey that goes from cheap to peak, they end up with a shoulder fare.
So, given my example with Reading, the person who arrives at say 10am but booked to catch the 11am, assuming that both trains are ‘cheap’ would have the right to just board the earlier service and be on their way. If a person arrived late at say 5pm (peak) having already pre-booked a cheap rate train at 3pm, they would simply have to go to the ticket office and pay the price difference - taking into account what they have already paid.
Surely, such a system would be more user friendly and make better use of what will become an excellent train service. When special events are taking place - such as rugby in Cardiff, higher rate fares would apply on that day only and in the direction/time of predicted increased flows.