Paul Terry wrote:

So the interesting legal point - can a TOC legally enforce a penalty fare
if
it can be shown that the correct ticket was not available to passengers at
the starting station?

Probably not (or at least the PF can be appealed against). The DfT make
the situation clear he

http://www.dft.gov.uk/pgr/rail/legis...policya?page=7

Those rules don't explicitly take into account the nuances of the machines
not being able to issue all reasonable tickets. The touch screen machines
can generally handle any turn up & go fare, and the old button machines
usually had every single direct station and reasonable interchange on them,
with permit to travel machines covering some of the gaps, but nowadays a lot
of machines aren't

But with OEPs rapidly becoming available on automatic ticket machines
across London, it would probably be necessary to establish that the ticket
machine was broken and there was no other one available nearby.

Yes but as stated elsewhere on the thread there are a number of stations and
operators who don't have the Oyster pads on the machines - National Express
doesn't have them at Forest Gate or Stratford; Barking (which operator?)
didn't have them before Christmas. Okay Stratford has TfL machines as well
but the others, particularly Forest Gate which has only one machine and
isn't staffed in late evenings, don't. I'm not sure the presence of nearby
newsagents with different opening times who have Oyster facilities would
suffice as alternatives. (And also yesterday when in one of the ones here I
asked for reference if I could get an "Oyster Extension Permit" there and
the man at the till looked at me blankly so I said that it seemed to only be
available at stations. So a further question is whether passengers can be
held responsible if they can't get the product because somewhere along the
line the information has not reached the till staff.)

So the scenario is not the deliberate or accidental dodger being caught
unaware but rather the conscientious passenger who is unable to get the OEP
because it's not easily available and certainly not at the station where
they're beginning their journey.