On the delay attributing - let's say it was driver error. (Not saying it was, no evidence to suggest it was before the mafia want my head on a pole) who would be liable. GTR for causing the issue or network rail for the time it took to clear it up? I guess we get similar problems when pantograph faults bring down the wires.
The incident would be split, with an agreement on the percentage apportioned to each party through negotiation (and evidence).