PPS : The above mentioned jigsaw image comes from a 2011 entry in the blog Steam Trains and Jigsaw Puzzles. Looking around for more information on the artist I came across this on the Bear Alley blog:

I collect steam train jigsaw puzzles as a hobby and currently own around 400 different examples. T. E. North was a prolific railway/transport artist during teh mid 20th century and his poster/illustrative style artwork was ideal for jigsaw puzzles. Manufacturers included Victory, Ian Allen/Ponda, Valentines, Philmar (all wood) and Good Companion/Tower Press (cardboard). I wrote a book on the subject of steam trains and jigsaw puzzles three yearsa ago but always found [North] difficult to research. One snippet I can add to your own research is that a man named Thomas Edward North died in Castle Hill Hospital in Cottingham - 16 April 1985 (born 25 September 1916). Cottingham, of course, is close to Hull, where we suspect he worked from.

Given the above I think we can accept Mr North's illustration as an authentic representation of a Fowler Royal Scot Class loco in BR Caledonian Blue, confirming the OP's friend's recollection, assuming it was prior to 1952.