It makes we wonder if the on-train caterers aren't missing a trick. The sheer number of catering outlets at major stations, together with customers stocking up for the journey, certainly indicates that people want to eat/drink on long journeys. Maybe if the on-train buffets and shops offered better value, then many of the coffees and snacks I see being brought onto the train might instead be purchased onboard?
Maybe a Greggs franchise on board perhaps? With the same prices as the shops??