I may be wrong, but didn't the Canadians call their 4-8-4's "Selkirks" or somesuch?
No, the CPR called their two 4-8-4 locomotives K1-a. The Penny's 4-6-2 was also a K. The roads did what they wanted because they were paying for the locomotives.
The Selkirk was CPR's 2-10-4. CPR crews just called them after their class number. "Fifty-nine hundreds", for example. The reason the name Selkirk was chosen is that the engines were used, and intended, for service as head end power for the longer passenger trains and freight consists into the Selkirk Mountain Range in the Canadian Rockies. They didn't also name their other engines "Monashees", "Purcells", "Coast Range", etc.
I'll say it one final time, but this time use a little more analytical thinking: it was a business decision, from the marketing department, to name trains and to name locomotive classes built in the middle to late Depression to drum up business. The CPR named their first locomotives built during the Depression....what? "Hudson". What was its Whyte Notation? Why, strangely, a lot like the NYC's own namesake with, coincidentally, the 4-6-4 wheel arrangement. However, when passenger service was flagging, some roads came up with Greenbrier, Kanawha, and other names for their newer super-power steamers (with feedwater pumps, feedwater heaters, thermic syphons, arch tubes, super-heaters, and bigger fireboxes). It was a way to generate excitement over novelty where the companies promised better service for the same money, and with new modern power. Advertising. To link it to the CPR, after the Hudson the only engines they named were the Jubliee Class 4-4-4 and the Selkirk 2-10-4. All at the same time...the middle of the Great Depression when ALL roads were desperate to drum up more business.
BTW, a Canadian Jubilee 4-4-4 holds the official speed record for a steam locomotive in all of N. America. 112 mph, and then only because of a test on new brakes. The chief engineer ordered the hogger to run it up until he was running out of track and acceleration and to then do an emergency brake test.
Sorry, Toot.
Marketing.