In message , Tim Roll-Pickering
writes

How would you solve the other problem of people with season ticket
travelcards starting journeys outside London? e.g. if I go to stay the night
in Surrey, I cannot get an overnight return extension - I have to buy the
ticket on the day. So I'll get one to the first station inside the zones but
do I then have to jump off at that station, touch on a pad and then waste
time at a remote outpost waiting for the next train?

Assuming we are still talking about OEPs (the subject of the thread),
you don't need one for the return journey. If your season is on Oyster,
you have PAYG and your Surrey station is within the London zonal system,
the Oyster system will work out the correct return fare.

--
Paul Terry