I think I might be wrong in relation to East Midlands Trains. This is the response I got from them:
Ref: 862184
Hi Mr (Firstname removed) Potter
Thanks for your email regarding ticket purchases.
We allow tickets to be purchased on the train by our conductor if there is
no option to purchase them at your station of origin. This would be a valid
reason to do so if the ticket machine is broken and the ticket office is
closed/No ticket office at the station. If there is any option to purchase
tickets at a station we will not be able to sell tickets on the train.
Thanks for taking the time to get in touch.
Kind regards
(Name removed)
Customer Service Centre
Tel: 03457 125678
Email:
getintouch@eastmidlandstrains.co.uk
I subsquently called the company to clarify their position, I was told that the sign only applies to trains operated by Greater Anglia and not East Midlands Trains. This is in spite of the Ticket Vending Machine not being visible from Platform 2, which is directly accessible by a side entrance. I was also told that you are allowed to buy a ticket using cash onboard a train departing that station but not using a card unless the TVM is out of order. Does that mean that if the guard is uncooperative, the guard doesn't come through and there is a revenue block at the destination (and it's not on Greater Anglia's terrority) the RPOs board the train and carry out a ticket inspection a passenger travelling from Platform 2 towards Peterborough and beyond could potentially find themselves being sold an undiscounted single ticket if they don't have enough cash but do have a card?