Thanks for the information to date. Nobody yet has answered the question as to why there ARE published fares from Frome to stations further West. I am sure BNM knows the answer but it is probably just one of those old anomalies.
Now the real question is - that should I wish to use the 08.02 FRO» /08.25 WSB» to TAU» can I buy an Off Peak Return (Code WG). It would be preferable to do this on line so that I do not have to argue my case but there is no obvious way of doing so since there is no published fare available on National Rail or Mixing Deck sites. This fare is the same price from FRO or WSB.
Any further thoughts?
The only answer I know is the one you've given. An anomaly.
You could ask
FGW▸ if they will expressly permit what may well currently be a local instruction, by amending the Electronic Routeing Guide to include Taunton as a valid destination via Westbury using the 0802 from Frome. With Frome having such a poor service generally, it does make sense for the 0802 changing onto the 0825 at Westbury to be valid to Taunton, as it is for stations further west.
Without such an easement expressly permitting such a journey, anyone wishing to travel from Frome to Taunton can not do so before 0941 for a 1053 arrival, according to journey planners. That really is poor connectivity for two towns in the same county. Only those who interrogate the system further, as WSW Frome has, will find that the JP allows them to go to Tiverton and beyond, but not Taunton.
Whilst journey planners don't currently allow such a journey, I don't see there being any problem doing it. As SDS says, there may well be local instruction, but if not, it would be very harsh on FGWs part to penalise someone travelling to Taunton via Westbury when it is perfectly legitimate for others to travel to Tiverton Parkway, Exeter and so on.
What also needs fixing for this journey, and the others further west, is the JP only offering the Anytime (SOS/SOR) fare from Frome via Westbury at 0802. You are connecting into an Off Peak (SVS/SVR) service leaving Westbury at 0825. That should be allowed according to the
restriction code text. Potential overcharging there.
WSW, I suggest you raise these points with FGW. It may take some escalation before you get a decent answer - fares and their arcane restrictions are little studied by the average Customer Service bod! Let us know how you get on.