In article ,
Neil Williams wrote:
My understanding in that situation is that, if you left the train
early on one of those tickets, you would be treated as if you had
completed the journey you did with no ticket at all (as by doing so
your ticket was rendered invalid, and thus it ceased to exist as a
valid ticket).

On the other hand if you were met at the barrier by a staff member who
says your ticket is invalid, you might say `oh I was just looking for
the sandwich shop / phone topup / etc and I'm going to get on the next
train'.

Not necessarily the most plausible story but hard to disprove. Is it
permitted to needlessly change trains ? I can think of any number of
reasons why you might want to.

--
Ian Jackson personal email:
These opinions are my own. http://www.chiark.greenend.org.uk/~ijackson/
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