To come back on a few of your points airsouthwest:
- Yes the IET's are coming on the rails, but they will only improve journey times between Wales and the SW and London by a few minutes, compared to the 40 year-old HST's they are replacing. This is at least in part due to the infrastructure, especially in Devon and Cornwall, where the main lines are bendy and hilly (by railway standards, with some of the steepest "banks" in the UK) and the cost (and environmental impacts) of fixing that mean it's never going to happen.
- Crossrail will not speed up long-distance rail travel, but will be great if, for example, you live in Maidenhead and commute to Canary Wharf.
- which Flybe route were you talking about? If EXT-LCY, it takes around 50 mins on average, which is around 1.5 hours quicker than the fastest train to Paddington (as far as I know).
Bit off-topic I know, but interesting as debate about the future of domestic air travel.