I often think that the railways are mis-identifying the market they are competing with. London to Amsterdam in 5hrs 15 min - thats at least three hours longer than flying and rather puts a damper on a long weekend.
For short journeys air has a high fixed cost and low marginal costs. It doesn't cost an airline much more to fly from MAN - CDG as LHR - CDG (actually given the time it takes to taxi at LHR probably very little more).
Railways in the UK are great for getting to, from and around London but not much good for much else (some local regional journeys excepted). You are never going to compete with air from Plymouth to Edinburgh - even if you have to change at BHX.
It doesn't have to be like that. To see what I mean go to Switzerland. You can get from almost anywhere to anywhere effectively by train. Think of Zurich main station as the ATL of the Swiss rail network.
No, rail is competing with the car and to compete effectively it needs an integrated network. It just thinks that it is competing in the main with aviation.
As a matter of interest there is a group called the Swiss Railway Society that organises day trips by easyJet to GVA or ZRH with their user friendly rail stations where they trainspot for the day. Not quite my cup of tea but think about it, you couldn't do it without the plane but wouldn't do it without the train.
Anyway thats your two pennys worth from someone who wants to see a vastly improved rail network but thinks that building high speed lines is not the best way to spend limited funds.