Originally Posted by
globalste
Unless it has changed recently, there is only F on the FGW sleeper.
EDIT: I now understand, you were talking about the Caledonian Sleeper.
I was, and the rules are different. But so far as I'm aware the FGW sleeper is all Standard, not all First. On both, it used to be the case that to have a single berth you had to pay for a First Class ticket, but this was changed when the single supplement was introduced on fGW. ScotRail used to have a "Caledonian Solo" supplement for single use of a twin-berth cabin but this seems to have gone.
The seated coaches on both are First Class style (i.e. 2+1 seating), I believe, but are declassified for the use of Standard ticket holders.
http://www.seat61.com/Cornwall-sleeper.htm confirms.
Neil