From The Independent of today's date:
The Government may face a legal challenge to its £33 billion HS2 high-speed rail project, it was revealed today.
Opponents of the scheme are also contacting the European Commission over concerns about HS2's environmental impact.
HS2 rail link may face legal challenge - UK Politics - UK - The Independent
Just imagine how many challenges a Thames estury site would have. It is never going to be built.