St Pancras vs St Pancras International - different itinerary, same ticket?

[4COR]

Using the forum's ticket sale site, I get slightly odd behaviour for the following journeys:

Wed 9th Aug, travelling at 6am
Oxford (OXF) - St Pancras (STP)
And comparing to
OXF - St Pancras International (SPX)

With no Advanced Options set, the journey to SPX insists on sending me via the Elizabeth Line to Farringdon, back to STP and then the 1min "walk" to SPX.

The journey to STP sends me on the same OXF-Paddington train, and then just says "Tube to STP", resulting in an itinerary that's 27 min quicker. A CIV ticket to London Eurostar (LOE) does the same as the latter (adding on the extra connection timings as expected).

I'll just get the quickest route anyhow, but what's going on here that makes it give two different journeys, even though they both go through STP?

 

[SargeNpton]

STP is the code that should be used by public-facing systems for all domestic services and fares at St Pancras: Southeastern, East Midlands Railway and Thameslink, regardless of which part of the station the trains run from/to.

SPX is the code used for Eurostar services - and no retail system should really be offering that as a destination for GB only journeys.

 

[4COR]

SPX is the code used for Eurostar services - and no retail system should really be offering that as a destination for GB only journeys.

Ok - so this is data oddness then. It won't sell me a ticket with SPX as destination - it just offers a ticket to Underground Zone 1 (just as for STP)

 

[SargeNpton]

Ok - so this is data oddness then. It won't sell me a ticket with STX as destination - it just offers a ticket to Underground Zone 1 (just as for STP)

There is no "STX" code in any rail industry source data, but there is "SPX".

If RailUk is showing STX then I have no idea where it's getting that code from.

 

[4COR]

There is no "STX" code in any rail industry source data, but there is "SPX".

If RailUk is showing STX then I have no idea where it's getting that code from.

Sorry - yes - that's a brain/finger error - I'll correct the above...