I had a memory that there was an easement involving going to Gobowen via Shrewsbury. It's no longer in the Routeing Guide, having been
removed in 2016:
Routeing Guide Changes said:
Easement 030024 is withdrawn. It was first published on the 18 August 2003. Since then a new Routeing Group at Wrexham has been created which meant that the easement has had no impact on permitted routes. This is because both the origin (Gobowen) and destination (Wrexham General) share a common routeing point and the journey via the applicable location of the easement (Shrewsbury) would fail the steps of the Routeing Guide by not going via the shortest journey. Therefore Journey Planners and manual calculations of Routeing Guide permissions will have ignored the easement.
Easement removed
030024: Journeys from Gobowen to Wrexham general and beyond may doubleback via Shrewsbury. This easement applies in both directions.
This easement allowed doubling back via Shrewsbury, but not apparently not just travelling via Shrewsbury (as I thought I recalled). Chester-Shrewsbury had some two- or three-hour gaps in its service back then, but a glance at a
2004 timetable shows no examples of trains passing through Gobowen non-stop, so it could never be quicker to go south to Shrewsbury then north through Gobowen (or vice-versa). The easement actually predates ATW's franchise, but the skeletal remains of Wales & Borders' website available through archive.org shows they didn't offer pdf downloads of timetables, so I can't check what their service pattern was like.
If, on the other hand, the easement actually allowed travel
via Shrewsbury (and not just doubleing back) then it would effectively enable travel between Liverpool and Gobowen via Shrewsbury and Crewe. While it's not the case today, in the past that would have meant a Gobowen-Liverpool tickets would have been much cheaper than Liverpool-Shrewsbury, and valid via Shrewsbury (in NFM64, a SDS LIV-SHR was £12.70 whereas LIV-GOB was £5.70).
That significant price difference makes me think that at some point, the SDS fare (and related returns) was given the routeing 'via Chester', and a new 'any permitted' ticket at slightly more than LIV-SHR was introduced. Since then we've had fares simplification, which muddies the waters when trying to look back and see what happened, and the new routeing point of Wrexham General has been introduced (though I don't think that in itself affected anything).
I reckon that this easement did in fact allow travel via Shrewsbury (as opposed to just doubling back) and that the 'any permitted' fare is intended to reflect travel via Shrewsbury, especially given the price difference (£40.50 vs £38.90 for LIV-SHR). With the removal of the easement, the 'any permitted' fare became useless.
On another note, the 'via Chester' fare would have been better specified as 'via Wrexham', as it would then include travel via Shotton or Chester, while still excluding Shrewsbury. TfW are planning on overhauling several fares in North Wales in the new franchise, but I suspect they may not tidy this mess up unless someone brings it to their attention. Perhaps one of our fares advisors would have an idea how to go about that.