I just threw it into the planner and it told me it can be done in 4h13m (though most journeys are considerably worse) with a single change at Carlisle.
Neither Deal nor Rye are significantly farther from London by rail than by the best road route.
It might not suite everyone as you are on the bus for a fair time with no toilet.
There is no direct bus from York to Whitby, only from Malton, and at present there are only 2 journeys per day on this route. It is probably simpler [and quicker] to book a rail ticket through to Scarborough and then take a bus to Whitby from there - the service appears to be 2 hourly and takes about 1 hour.
Can't believe I forgot East Kilbride! Certainly number 1 in Scotland.
Using the Covid (Sunday service?) timetable is stretching a point, I would have thought - but I suppose in a local context Llandovery could be called a major townI'm not sure whether I'm on the right track (no pun intended!), but how about Llandovery (assuming it meets the criteria)?
Travelling on Monday, the first service with a connection to London is the 12.38 to Shrewsbury (13.13 - 15.32). It's then necessary to change at Wolverhampton (16.07 - 16.14) and Stafford (16.27 - 16.41), arriving at Euston at 18.03.
There's no return train that night, so you'd have to wait until Tuesday, when you have a choice. Your first is from Paddington at 07.48 to Swansea (10.34 - 11.14), arriving at Llandovery at 12.36 - two minutes short of 24 hours! The second is from Euston at 09.10 to Crewe (10.45 - 11.11) then to Shrewsbury (11.42 - 12.04), arriving at Llandovery at 14.16 - 25 hours and 38 minutes!
The journey from London and back is comparatively short, as it can be done on one day. It takes 5 hours 26 minutes out via Crewe and Shrewsbury, and there's a choice for the return - via Swansea (4 hours 37 minutes) [Total 10 hours 3 minutes] or via Shrewsbury, Birmingham New Street & Moor Street, which takes 6 hours 12 minutes [Total 11 hours 39 minutes].
Someone's going to tell me that it doesn't count now … but that's life!
Using the Covid (Sunday service?) timetable is stretching a point, I would have thought - but I suppose in a local context Llandovery could be called a major town
On a normal Monday there is an 07:30 Llandovery to Crewe, arrive 11:11 then 11:22 Crewe to Euston arrive 13:00 so 5hrs 30.
Hmm, although an advertised connection, 11 minutes is a bit tight especially on the return as there is no alternative train back to Llandovery from Crewe.
Presumably one day next week, when the service is 2 trains per day each way? Search engines are updated on a weekly basis with reduced timetables.
This was the OP's earlier definition of a "major town" and, as such, it tends to exclude quite a few towns located out in the regions.
Another option for Reading - Waterloo is via Basingstoke, but you can't buy a single or return ticket valid that way. I used to commute the route daily, but using a Basingstoke - London travel card season valid via Reading or Woking, which was exactly the same price as a Reading - London season. I usually caught the shuttle from Reading West, changing onto a fast at Basingstoke. Far less crowded both ways than going via Paddington and avoided using the awful Bakerloo to get to my south bank workplace. About the same overall journey time door to door. Always had the option of going via Slough or Staines if expedient on the day. Often used the Staines route if I had to go straight to Croydon for work reasons as nothing fast in the morning peak from Basingstoke stopped at Clapham Jn.
