I know that opportunities will be much more restricted since "Balkanisation" but are there any examples left within any of the TOCs where a form of traction performs a "filler" journey on a route such a type would not otherwise be used during what would otherwise be unproductive time?
My memory goes back to the early days of when BR Scottish Region was rebranded ScotRail under Chris Green and you got odd but sensible things such as Euston-Glasgow Central 87s and coaches starting back from/extended to Ayr, HSTs from Inverness to King's Cross starting back at Elgin etc.
Well, at one point the entire Edinburgh to Aberdeen service was more-or-less entirely resourced through "marginal time" working!
A mixture of HSTs to/from London, one to/from Leeds and the daily XC service. (1985 timetable).
You also had the Aberdeen-Plymouth starting back from Elgin in at least one timetable period (1984?).
Glasgow QS to Edinburgh Express services formed of through HSTs to/from London, slotted into the srandard timetable.
Initially a Perth-Kings Cross HST (1982), which later became the Highland Chieftain (1984). Don't remember any starting back at Elgin though. The Sunday southbound ran via Elgin and Aberdeen for many years, as the HML was shut until the afternoon on Sundays into the 1990s.
The Edinburgh-Penzance HST was extended back to start from Dundee in 1983 and ran as an morning all stations (bar two) stopper within the regular interval timetable. The return from Plymouth did the same in the evening.
The Royal Scot as you mentioned, starting back from Ayr, running effectively a high-quality Ayr to Glasgow morning commuter and and evening equivalent back (though I don't think the return working was the Royal Scot service).
Probably a couple I've missed.
Examples did exist on other regions, but I think the Scottish Region/ScotRail possibly had the largest number of examples?
