Certainly the Poacher line 153s would benefit from a vending machine, it's actually a decent chunk of time on board from Nott'm to S'ness if going via Grantham. They could be installed above the cycle racks, it would only need to be the size of a mini fridge. If they sold premium products like Kettle Chips, Joe & Seph's Popcorn, Dormen Peanuts, Folkington's juices, Harrogate water & other luxury yet un-perishable products, they could all be neatly packed in. Selecta machines charge £1 for Kettle Chips at stations, so the price could obviously be increased for on-board convenience, perhaps something like £1.40 for crisps, £2 for popcorn and Coca Cola/Sprite. It could be quite a lucrative operation, if marketed well. Northern 158s, which have no catering (bar the Carlisle services) could also benefit. They could install machines where the old BT Payphones were. There are plenty of little nooks and crannies what aren't large enough of a space to install aditional seating, yet could be used for a vending machine.
