There were still Plymouth boat trains with this stock running until the vehicles were withdrawn in 1962. I can recall them occasionally coming through Taunton that summer. The Up train used to shadow the Up Cornish Riviera, which at the time was one of the few trains to pass Taunton nonstop, just at lunchtime (in fact at about 12.55, it was the signal for me to go home for lunch!). All the up main distants would come off and the Riviera, with a Warship diesel, would come through at about 80mph. Just a couple of minutes later all the up distants would come off AGAIN, and then the boat express would pass at equal speed, Castle-hauled to the end, and the always cleanest locomotive you saw all week, the Laira preparation gang must have made a special effort for it. About 4 saloons and a bogie van.
I believe the ship which called at Plymouth to the end had come from South America. There's an Ocean saloon in Didcot museum, when I look at it I wonder if (quite likely) it was one of those I saw whizzing through at speed, long ago.
One of the best-regarded television plays features just such a Continental boat train trip, from Ostend to Vienna. Called "Caught on a Train", by Stephen Poliakoff, as well as being a well-done piece of drama, it has a whole range of interesting shots of Continental services back in 1980s loco-hauled days, all shot in the correct locations for the programme (one of those things only us lot would notice). On DVD.
I trust you weren't as demanding to the American as Frau Messner was
http://www.imdb.com/title/tt0080507/