I think that is the disruption that I was told caused the cancellation.
So it raises two issues.
1. Was there a person hit by train near Penzance on 16th which is what GWR reply said to me?
2. If not is it reasonable for GWR to refuse compensation due to an incident the previous day?
I see this as having
some similarities to the EU flight delay system (though there are many differences too) - where compensation is not payable if the
direct cause of the delay is outside the control of the airlines, as well as outside their normal function (e.g. lightning strikes are to be reckoned with when flying metal objects through clouds, therefore it is not deemed an extraordinary circumstance, but security alerts are not to be expected and are outside the airline's control hence they are).
In the same way, if the
direct cause of the delay is "entirely outside the control of the rail industry" (NRCoT 33.4), such as freak weather or a person hit by a train where suitable precautions have been taken, then I agree that GWR are not obliged to pay compensation under the NRCoT scheme. However, if the above are mere
indirect causes and the
direct cause of the delay is GWR being unable to shift their units and staff around as needed, then I would not say that it is "entirely" outside their control (as they could, if they were willing to spend the money, have more spare units and staff). In this way, liability could not be escaped - in the same way that if your aircraft is late into the airport because of bad weather at its origin, that does not exculpate the airline from compensation liability as the
direct cause is the fact that they overutilise their fleet and don't have enough backup and recovery time!
Obviously these are all very technical arguments and unless you are willing to study them in depth or engage a solicitor to do so for yourself (both of which would cost large and unrecoverable amounts of time and money, respectively), in order to present them at Court, then I think it unlikely you will be able to force the compensation out of GWR. However, it is still entirely possible they may pay out at least something as a "gesture of goodwill" if you pester them enough. This is all of course ignoring any possible consumer rights avenues - such as if GWR could be deemed not to have performed the service with reasonable care and skill - in which case a price reduction might be applicable.