[BBKing]

Spot on there. Unpleasant answers follow:

Southall - Train not turned because GW would have had to pay Railtrack for the privilege of taking an empty train round the triangle at Swansea - under a properly run integrated railway the cost of cancelling the train would have been greater than the negligible cost of turning it, so it would have been turned. Not having been turned, it should have been cancelled as unfit to be in passenger service, but this would have incurred compensation payments and made the figures look bad, so it was run. End result 7 dead, rolling stock destroyed, track torn up, £1.5m fine.

Privatisation caused the previously non-existent pressures to run an unfit train to take precedence over sound engineering advice.

Mind you, the signal that was missed (at yellow) was grossly misaligned and incorrectly designed, which brings us to:

Ladbroke Grove, where a badly designed layout and a badly trained driver missing badly sited signals caused an appalling crash. The layout was designed by Westinghouse and BR in the early 90s under the assumption that all trains would have automatic train protection in case of missing signals. In fact two out of the three types of train on the route had ATP, the exception of course being Thames, as BR didn't fit it to their trains in the years immediately pre-privatisation and Thames didn't in the years immediately afterwards, and the HSE didn't press for it, being too busy nitpicking about footpaths by the trackside and other major threats to railway safety.

The layout at the points was therefore designed on the basis that no trains would go through a red light, so they could be left safely pointing in the direction that was the easiest for the computer signalling to cope with, which unfortunately meant a possible head-on collision in the case of the signal being missed, instead of a possible sidelong collision with a train travelling in the same direction. So cost cutting on the original design, assumptions about the nature of the traffic that were never revisited after privatisation (Railtrack would have said 'Thames has to fit ATP' and Thames would have said 'RT has to make the layout safer' and no one was there to knock their heads together).

Interesting, if slightly irrelevant point about the idiocy of privatisation, the only company barred from bidding for passenger rail franchises in the UK was the only company with any experience of running passenger services in the UK, i.e. BR. In Sweden, which has had private railways a lot longer, the old state railway is still there and running services in competition (and sometimes cooperation) with private companies.

Ding-ding!