An old (11 years ago) but very interesting article about the failure to raise speeds on the WCML, and how moving blocks on mainlines were still the stuff of fairytales then. Perhaps some relevance to recent news about HS2 being threatened with cancellation.
pt.1
http://www.theguardian.com/world/2004/apr/01/transport.politics
pt.2
http://www.theguardian.com/world/2004/apr/01/transport.politics1