I'll pick-up on a couple of your points. You may remember that the first attempt for 'higher' speed rail was the idea of tilting trains. Using existing rail lines the train would tilt - a bit like a motorcyclist leaning into the bends- and consequently greater speed could be attained. Problem was that it made people feel sick and the tilt mechanism did not return to the horizontal in a few of the trials. The idea was an example of the innovation I mentioned in other posts. A case of what can we do with what we've got already.

Well, I's been doing my research. Tilting trains is far from dead http://www.machinery-market.co.uk/news/9256 But what is dead is Britain's ability to make them or any other train. Although I do believe we still have some ancient goods rolling stock manufacturer...on the brink of collapse the last I heard.