Woah, now this could be a big topic ... this country's rail woes began about 50 years ago with a shift towards road transport which was perceived as the flexible, modern way forward. Governments of all colours have favoured road development, choosing to fund the railways almost as an 'overflow' system carrying traffic that physically can't fit on the roads. Investment has been insufficient to keep pace with technological advances, the need to get to more places and faster, and, worst of all, simple maintenance and renewal of the infrastructure.
The Hatfield crash is now often quoted as the point in time when things went horribly, horribly wrong - speed restrictions and the like - and is now seen as the beginning point of a period of turmoil on the railways now forecast to last another 10 years (you often hear predictions of when punctuality will return to 'pre-Hatfield' levels). However Hatfield, in which a fatigued piece of track snapped, allowing a GNER train to de-rail, simply brought into focus the dangerous state the railways were being allowed to fall into.
And while there has been more apparent progress towards improvement this time, there is still a strong suspicion that once again, the Government's resolve fades as the news drops off the front pages. After the Ladbroke Grove disaster, John Prescott pledged to spend whatever it took to install Advanced Train Protection across the network, before perfomring a quiet u-turn when confronted with the cost and opting for a cheaper alternative (which, even if fitted, would not have prevented the Ladbroke Grove collision because the train passed the red signal at too high a speed). Similarly, pledges of cash for major upgrades have faded away, with Network Rail being 'encouraged' to lop £2bn off its new budget request, and news now that it may get a further £1.3bn cut. NR has indicated that it is maintenance on lesser-used lines that will be put off if this is the case. Truly, what goes around, comes around...
(As for the London Underground map, see here for a geek's treasury of information and history:
http://clives.members.easyspace.com/tube/tube.html )