The New Adlestrop Railway Atlas is a historical atlas of Britain's railways, currently in progress. It shows lines and stations currently open, together with those that have closed. Here is a link to it.
http://www.systemed.net/atlas/

It just goes to show what we could have had if decisions with long-term consequences had not been taken purely in response to short-term financial constraints on an authority.

Thanks Lee I have been trying to find a map like this for ages.  Some areas look horrific with whole swathes of lines cut such as North Devon amongst others.