Question - Is the Gold Card discount allowable on the limited Hull Trains services which stop at Stevenage?
Interestingly, the Hull Trains website will show Gold Card discounted tickets, and indeed Network Railcard discounted tickets, as being valid on its services, and will presumably allow seat reservations, notwithstanding that it is not listed in the relevant T & Cs as being a participating operator in either scheme.
I make no comment as to validity.