I used all these trains a number of times in the 1980s. Always on the cushions though; to this day I've never been inside a sleeping car. They were an ideal positioning move for the 06:35 Inverness > Wick/Thurso and 06:55 to Kyle, although there was about 2 hours festering to be endured in Inverness. You always got woken up at Perth by the shunting joining the two portions together.
On one trip in 1984 I used the Edinburgh > Inverness sleeper one night, and the Edinburgh > Bristol the following. On the Bristol, there was an ETH problem (it was February!) and by the time we got to Birmingham we were completely frozen. I was actually quite worried about my dad who is quite bronchial. There was a steam heat peak with working boiler waiting at New St to take over from the 81 that had worked from Glasgow. Never have I been so glad to see a loco!
In the early to mid-80s other sleepers were about 4 departures a night from Kings Cross to Edinburgh and Aberdeen; a nightly Glasgow > Aberdeen working; departures from Euston to Glasgow (went via Dumfries), Stranraer Harbour, Liverpool/Manchester (split at Stafford), Barrow in Furness, and Inverness/Fort William. This last went via Mossend Yard where it split and and a duff hauled the Inverness portion onwards. The Fort William portion (2 sleeping cars, 2 standard mk II aircon seating coaches) ran into Glasgow Queen St, where a 37 + 2-3 mk Is or older mk IIs were attached and the train went out as the 05:50 morning departure to FW. There were only 2 or 3 trains a day from Glasgow to FW then, and if you missed that one, on winter weekdays there was nothing else until 16:50. After the mk III sleepers replaced mk Is on this service, 3 class 25s were converted to mobile ETH units to be placed between the 37 and the stock to power the heat and aircon. Before this the dual heated mk I sleepers could be heated by the loco's boiler. This lasted only until the 37/4s came in (1986?)
There was also a single sleeping car attached to the Holyhead > Euston train that left Holyhead about 01:30 am. There was no sleeper service the other way, the sleeping car being moved to Holyhead empty on a Euston > Holyhead daytime working.
From Paddington there was the Night Riviera, which ran pretty much as it does now, except it stopped at Bristol and seated passengers could use it to/from there.
Most sleepers conveyed quite a bit of seating accomodation, much more than the meagre amount on today's Caledonian Sleepers. They were usually just ordinary non-aircon mk IIs though, without the luxury of the reclining seats you get now. Mk III sleepers were progressivley introduced on the more prestigious routes first, with the last Mk Is going from the internal Scottish sleepers by about 1985.
There were also overnight seating only trains, mainly mk I stock, running on the ECML and WCML to destinations in Scotland, serving most station en route, including Leeds. Although the ECML workings were usually class 47s, anything could drop on these, from a 31 to a 40 to a 46. Fishguard had an HST to Paddington at 01:50 which I used a number of times, and there was a great overnight train from Waterloo to Weymouth. Most mail trains conveyed an SK or BSK to provide limited passenger accomodation overnight, and these were really useful services