Ok, that is understood but I still think that it is harder to make the case in the UK than in France because of the shorter distances, higher population density (compared with rural France) and different planning laws which could well mean a lot of public enquiries, land sales, Swampy building a new treehouse, etc.
I'm also not convinced that building HS2 will make normal rail travel any cheaper, and the cost of rail travel needs to come down to compete with road travel even with petrol going through the roof.
edit: I just checked on the East Coast site and a York-Kings Cross return is £166 standard class for an "EC Advance" while for some reason an anytime return is £105. It is still cheaper by car, with the added advantage that you can take your wife, kids and dogs for free.