I cannot see what it has to do with anybody what you carry as long as it isn't used to point out of the window on the way pretending to shoot the Deer seen from the train

Where would you draw the line at what you disclose to them of the contents of your luggage !!
I have read this post and thought maybe they have introduced X Ray machines like they have at Airports, if they haven't and you have packed your firearm sensibly how are they going to know.
If it is in an 'unusually shaped' package how are they to know whether it isn't fishing tackle, or are you expected to open it it for inspection at the carriage door?
If this is a serious matter being discussed I apologise.
As I haven't travelled on a train since the early sixties, if I were to travel with a firearm today I would have just packed it and travelled.