She said that since I wasn't going to cross the barriers at HRW, i.e. leave the station, then I should be able to get off at HRW and use the Overground to come back one stop.
This is appalling advice if true, as it gives the impression that not having to go through barriers is a main reason why you can doubleback, whereas in reality this is determined by whether the route is valid or not, irrespective of whether you have to go through ticket barriers.
I travelled south of HRW to Clapham Junction a year or so ago with some mates from work. I got my Oyster card from HDL that day and bunged a few quid on.
As has already been pointed out, combining a season ticket and an ordinary Single/Return ticket means that you can travel on a through train without having to stop at the point where you change from one ticket to the other. This is not applicable if you do not purchase a paper Single/Return ticket and instead use Oyster PAYG, due to the fact that you will need to de-train, and then touch in, at the changeover point, which in most cases would mean having to wait for the next train.
Yeah I checked that a few minutes ago when someone suggested a season ticket to HRW and not HDL. If I can use the routing guide to prove that LBZ-HRW-HDL is permissible with an LBZ-HRW season ticket I'll try that out and see what happens next time I encounter an RPI.
To address some of the confusion you have, the reason that LBZ-HRW-HDL is definitely a permitted itinerary is not that LBZ-HRW-HDL is arguably a permitted route
per se, but rather that once you reach HRW, you can then start a new journey at HRW, which is clearly also covered by your LBZ-HRW season ticket. Given that a season ticket has no break of journey restrictions along permitted routes, you can just break your journey legitimately at HDL.
Saturday is off-peak yes? I then have a disabled adults railcard which then reduces the price from £8.50 to £5.60. Would anyone mind confirming that for me? I've often felt like going to Euston at the weekend but wasn't sure if I could use two cards for the journey, i.e., use my season ticket to take me as far as Harrow and Wealdstone (or Headstone Lane!) and then use another ticket bought from Leighton Buzzard to cover the Harrow and Wealdstone (or Headstone Lane) to Euston and back.
You are perfectly entitled to use a combination of tickets covering the complete journey you are making, as detailed in NRCoC Condition 19. The ticket office at Leighton Buzzard should be able to sell you a ticket starting from Harrow.
I am unable to locate the £8.50 fare quoted above.
Yes indeed. Section A of the Routeing Guide defines doubling back as
It's debatable of course if you enter a station by rail and leave on foot, whether you have "passed through" the station on your journey, especially seeing your journey will end when you leave the premises! Personally I don't think you can be considered to be passing through a station that your journey ends at. But nothing is ever clear with the routeing guide...
I think it is within the spirit of the terms that entering a station by foot and leaving by train or vice versa should be considered as "passing through" the station, however I agree that it is very poorly worded.
c) The journey planner suggests travel via H&W as Headstone Lane is not a timing point in RJIS so the software cannot detect the double back. However it is well established that the Journey Planner offering a set of times is not of itself conclusive evidence that the route is permitted.
I believe fundamentally this is the main reason why the double-back is not detected.
Another interesting thread. Would the OP still not be at risk if NRE changed its journey planner (which it could do at any time), ie. a screenshot essentially just shows the validity of the fare that day but doesn't necessarily provide assurance that it will still be valid tomorrow (since validities/easements etc. can be changed).
For the reason detailed above, I don't think this is possible as the system cannot detect this particular doubleback.