I know you have a keen interest in trains, but I think your long ex would not be impressed with forum's interpretation for her. :-)

 

I cannot stick my hand up and say "me, me" because I stood at and used Holborn Viaduct many, many times - 4 departures an hour. Two were via Wimbledon to Sutton, Carshalton and West Croydon with a change at Herne Hill for Orpington; The train dallied there for a few minutes making a two way, cross platform connection in the way I would like to see at Westbury, with the Swindon to Weymouth service passed by the Bristol to Southampton service.  And two via the Catford loop and Eynsford to Sevenoaks, with a none-connection at Bromley South for Orpington.  Can't say I was even on the last train out or Holborn Viaduct, though - my on and off GF (her parents though I was too much below her) was a student nurse at Barts and after the last train of the night from Holborn Viaduct, there were other from Blackfriars right up to 00:20 (which I used) and the 01:02 which was later even than I needed.   I learned many things at the time, including to have a fallback plan / train.

I didn't wonder what the old track was - even in those days I knew. The more difficult question I had was "why on earth has such an obviously useful connection been abandoned?"

 
I knew it would be a mistake for this community to engage in a few rounds of Mornington Crescent: the game's immediately spilled over into reality. :-)

My destination's served by the 127 bus route so the railheads can be Carshalton, Wallington or Purley (and probably others) which is why a day return to London zones 1-6 is good for this (though not available from Bath) - and also, surprisingly, the Elizabeth Line and various Thameslink routings is useful too (though with Thameslink services at Carshalton, the gap between the train and the plaform feels like about 3 feet, it's a bit like stepping across the gap made by one open gate of a pair at the tail of a narrow lock**).

Thinking of 'Thameslink' and 'Gaps', the Carshalton chasm isn't as big as the gap there was between Farringdon and Holborn Viaduct. It must have been a lot of work to get the rail systems north of that gap and south of it to talk to each other, but the intensity and level of use of the resulting service is impressive.

Who among us hasn't stood on the platforms at Farringdon, looked at the dark and trackless mouth of the tunnel there and thought "I wonder what that once was?" Or, waiting for the last train on the platforms at a draughty, badly lit, ill-served and near deserted Holborn Viaduct, glanced down and thought "That's a funny place to see and abandoned trackbed, what's it doing down there?"

Mark

** OK, exaggerating but hopefully, once you know, a ramp's available on request.

 
The Reading to Waterloo normal route appears to be closed at Richmond, with the train diverted via Wimbledon.  If that's the case, under routing rules I would expect Reading to Clapham Junction or Waterloo to be offered on the direct train, but if you expand the route further so that it means you have to change trains between routing points, the train that runs via Wimbledon as part of the journey is no longer the shortest route so you have to go via the Hounslow loop.

Where are you actually going - Carshalton?   I wondered about changing you into Trameslink and Wimbledon and send you via Sutton, but it looks like that's closed for engineering too ...

 
tl:dr - online timetabling is becoming more strange.

*   *   *   *

This is for Sunday 4th January, out and back in a day. GWR is out of action east of Reading until 11am, while via Salisbury will not work out as Basingstoke to Woking is a bus and in any case the first Sunday train Bath to Salisbury is 09:36.

Leaving aside the ticket, the routing advice from National Rail is... fickle.

Using the 07:58 from Bath Spa, with Clapham Junction or London Waterloo as a destination, the system doesn't mention the direct trains but offers changes at Reading, Basingstoke, with a bus between Basingstoke and Woking, then Clapham Junction at 11:57.

Put e.g. Carshalton as a destination out of the same train, the system offers Reading to Clapham Junction direct at 10.57, so, an hour earlier.

With Clapham High Street as the destination, this throws up a 'Direct from Reading to Clapham Junction' option, but rather than Basingstoke, recommends changes along the way at Staines and at Barnes to give the traveller the experience of travelling via Hounslow and an 11:32 arrival at Clapham Junction.

(Plan 'A' is to ignore the National Rail routing confusion, have a ticket to Clapham Junction and use Oyster from there as it will offer flexibility of route)

Mark