In the same way that trains passing through and those taking the avoiding line at Didcot are both deemed to pass through Didcot routeing point, it is my understanding that all trains passing through the station or taking an avoiding line at Willesden Jn are deemed to pass through Willesden Jn routeing point. It appears that this is achieved in each case by having a mandatory timing point for all trains using the avoiding line.
Not directly. What counts for journey planners (as I understand it) is whether or not a train is timed at a location identified as having the station's CRS code in the current ttisf???.msn file in the
timetable data available from
ATOC's site.
Didcot Parkway (DID) is assocated with DIDCOTP (Didcot Parkway), DIDCTNJ (Didcot North Junction) and DIDCTEJ (Didcot East Junction). Didcot Parkway and Didcot North Junction are mandatory timing points, and everything using the avoiding line goes through Didcot North Junction, so trains which they're all treated as going through Didcot Parkway.
By contrast, Carnforth isn't associated with any point on the West Coast Mainline, so trains on that line aren't considered by journey planners to go through the station, despite physically going through the station premises.
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The Southern MKC-East Croydon services on the south WCML which would be used by the OP for this journey (unless he uses Oyster) do not pass through Willesden Junction. They turn right just before it.
My apologies, I should have been clearer. I meant "which alternative route
between Tring and London you feel doesn't pass through Willesden Junction". The route you mentioned one part of does, as that is where you would change between the two London Overground trains if you continued on to London.
Clause 14.1 of the Conditions of Travel say:
"Unless shown below, you may use a combination of two or more Tickets to make a journey provided that the train services you use call at the station(s) where you change from one Ticket to another."
If you change from one ticket to the other at Shepherd's Bush, and the train stops there, you may use any of the combinations of ticket referred to in this thread.
OK, there is an easement on the GWR that says that trains taking the Didcot avoiding line are considered to pass through the station, and the situation is similar.
Which easement do you mean here?
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But if a Wembley Central ticket is the same price as a Willesden Junction one, I don't see the point of buying the Willesden Junction one.
If.
A paper Wembley Central-West Brompton return "via Kensington Olympia" costs £4.90.
A paper Willesden Junction-West Brompton return "via Kensington Olympia" also costs £4.90.
However:
On Oyster, Wembley Central-West Brompton via Kensington Olympia* costs £4.80 if both outward and return journeys are at peak times, or £3.40 if the return is off peak with a railcard.
On Oyster, Willesden Junction-West Brompton via Kensington Olympia* costs £3.40 if both outward and return journeys are at peak times, or £2.70 if the return is off peak with a railcard.
A paper Wembley Central-Clapham High Street return "via Kensington Olympia" costs £6.20.
A paper Willesden Junction-Clapham High Street return "via Kensington Olympia" costs £4.10.
* The TfL site lists higher fares for a change at London Euston, but I don't know how much routes which avoid Kensington Olympia and Euston would be charged.
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