In message , at 22:31:23 on Thu, 22
Aug 2013, Clive Page remarked:
By a strict reading of the rules, the conductor was correct, a ticket
from Surbiton is only valid on trains that stop at Surbiton, while a
ticket from Boundary Zone 6 woule be valid on any train.

What I find surprising is that when you explicitly ask at a ticket
office for a ticket from the Boundary Zone to some station X, you are
often sold one from a specific station just inside the boundary. If
you query it they always say "this costs the same". That may be true
but it misses the point as the ticket validity is different. Is this
because some types of ticket machine make it hard for the ticket clerk
to select the BZ as the origin of the journey so they do this out of
laziness, or is there some other explanation?

It shouldn't be difficult, BZ6 is code 0072; see para 3:

http://www.perry.co.uk/avantix_for_dummies.html
--
Roland Perry