When you buy a ticket to travel on the railway network you enter into an agreement with the Train Companies. That agreement gives you the right to make the journey, or journeys, between the stations or within the zones shown on the ticket you have bought.
The National Rail Conditions of Carriage are also part of that agreement and they apply to all domestic (non-international) journeys by scheduled passenger train services of the Train Companies on the railway network of Great Britain.
These National Rail Conditions of Carriage set out your rights and any restrictions of those rights. The Train Companies may give you more extensive rights than those set out here; they may not give you less unless, in the case of some types of reduced and discounted fare tickets, a Condition specifically allows for this. The National Rail Conditions of Carriage therefore set out the minimum level of service you are entitled to expect.
A Train Company's ticket office staff will give advice about tickets, and any restrictions concerning their use, on an impartial basis unless the point of sale is dedicated to the sale of one Train Company's tickets.
If you prefer you can download a PDF version of the National Rail Conditions of Carriage here.