12:28 Dunblane to London Kings X
That's a service from Inverness, or are you saying that there's no direct northbound service from KGX?
The return service is 11 50 Kings Cross to Edinburgh but, unlike the opposite direction, flies straight through Dunblane.
Once weekly on a Sunday - no return service.
The Highland Chieftain calls at London, York, Darlington, Newcastle, Berwick, Edinburgh, Haymarket, Falkirk Grahamston, Stirling, Gleneagles, Perth, Pitlochry, Kingussie, Aviemore and Inverness most of the time.
The southbound journey on a Sunday also calls at Dunblane, Dunkeld & Birnam, Blair Atholl, Newtonmore and Carrbridge (not Dalwhinnie). There is no return journey to these stations; it operates to a weekday timetable heading northbound.
I think the Sunday Chieftains used to call at Peterborough; not entirely sure. I think that the Darlington and Berwick stops are fairly new as well (certainly Berwick). I've also always wondered why there's no stop at Dalwhinnie.
On the sleepers, Carrbridge is only served heading northbound (I think Falkirk is too; that might be
southbound only). Watford Junction is another one I think, and some stops on the Night Riviera (Lostwithiel/Par/Hayle) are only served in certain directions as well.