In peacetime, before WW2, almost all Perth to Inverness trains included both Glasgow and Edinburgh portions. The Glasgow part came from Buchanan Street (LMS). The Edinburgh part came from Waverley (LNER) via the North British route to Perth and was LNER carriages. There were usually carriages from both Glasgow and Edinburgh to Inverness via Forres and to Inverness via Carr Bridge with the parts being divided at Aviemore. Plus there were often local carriages from Perth to either Aviemore or Inverness. To further complicate the issue, when the LNER started using Gresley carriages with Pullman gangways, the LMS had to make sure the coach next to them was one with gangway adaptors fitted.