If I look at Manchester-London in a weeks time with a non-flexible ticket it costs £45 return (actually for £45 it's pretty flexible - you are just limited to one firms trains, a bit like that BA fare, and can't travel in the morning rush hour)
https://i.imgur.com/CNCzmKu.png
That's less than 9p per mile. What do you think a fair price would be?
This would bring the UK rail prices more in line with most other European countries.
£300 is gouging.
You can take the 08:46, arriving in Manchester at 12:13 - an average speed of about 60mph.
The £300 is an option that few choose, because that journey gives them major benefits. The money raised from that is plowed back into the railway and used to subsidise services to Harrogate, Holyhead and Hungerford
You do realise that a country needs 21st century rail service to be competitive interbationally?
Otherwise we would bring back bloodletting, leeches and snakeoil salesmen to get more choice in cancer treatment.