I can remember late 70s early 80s working in the West End (London) and travelling after the show on the Barrow sleeper as far as Lancaster ....
Both Manchester and Liverpool sleepers were well used. Bear in mind in the 80's the last daytime train from Euston was I think 20.00 to Manchester and slightly later to Liverpool. . .
The Sleeper trains to/from Barrow-in-Furness sometimes seem to have a connotation of being there mainly for the benefit of Royal Navy top brass and MoD boffins who needed to visit defence facilities in north-west England. No doubt 'the beds' did serve this purpose, but I believe these were also much more useful "multi-functional" trains.
They also provided late-evening departure / very early-morning arrival London services for substantial Lancashire settlements like Warrington, Wigan and Preston - in an era when the last northbound 'daytime' Inter-City departure to these places was around the 19:00 mark, and you were hard-pressed to arrive into Euston significantly before 10:00 in the morning.
On the Barrow trains you could leave Euston at 23:45, arriving in South Lancashire around the 02:45 to 03:30 window. Conversely, you had an option to depart southbound from Wigan or Warrington around pub closing time 22:45 to 23:15-ish and get into Euston in the wee hours of the morning, if that's what you needed to do.
I
almost used the up train once (on the cushions) from Wigan, but a last-minute change of plan meant I missed this dubious pleasure on that occasion - and the next time I had to consider this, the Sleeper was no more.
The Down Sleeper also called at the main Furness line stations around 05:00 to 05:30, with old WTTs showing leisurely dwell times at places like Lancaster, Carnforth, Grange-over-Sands and Ulverston. Presumably this was to unload London newspapers, mail and maybe parcels. I wouldn't be surprised if the train was marshalled with more vans than passenger carriages.
Do I remember correctly that, back in the day, there was usually a single Sleeping Car parked up all day in one of the bays at Preston, having been shunted off the previous night's Barrow train and awaiting re-attachment to the Up service later that evening?
Despite the shunting manoeuvre at Preston, for some (no doubt good operational) reason the Down train was booked to switch from electric to diesel traction at Lancaster. Just to add an extra bout of early morning clanking and banging of buffers to wake up Rear Admiral Melchett-Massingberd in his First Class sleeper.