The NCRT is pretty vague...
Clearly this is looking to restrict "long way round" on circular routes.
What about through trains diverted due to engineering - can I break my journey at intermediate stations which aren't on the normal permitted route?
16.4 Generally, you may start, or break and resume, a journey (in either direction
in the case of a return Ticket) at any intermediate station, as long as the
Ticket you hold is valid for the trains you want to use. However, this may not
be the case with some through services that take an indirect route. You may
also end your journey (in either direction in the case of a return Ticket) before
the destination shown on the Ticket.
INFORMATION: For example, where a train service makes a circular
journey, you may travel either way to the destination on your
ticket. However, you would not normally be allowed to get off at an
intermediate station where the fare would have been higher.
Clearly this is looking to restrict "long way round" on circular routes.
What about through trains diverted due to engineering - can I break my journey at intermediate stations which aren't on the normal permitted route?