To be fair, it wasn't the train crew who caused the problem: that was due to a security guard from a third-party contractor who locked up without checking the last train had arrived.
I suspect Northern will be having some stern words with their third party contractor.

Indeed, perhaps the
DfT» (who now 'own' Northern) should employ full time staff who are more likely to be aware of such things, rather than contractors?
Always good to be able to pluck a diamond from a turd!

Yes, call me strange, but I'd much rather go looking for diamonds than turds.
