I posted a request to a railway newsgroup for identification of the locomotive and this was the response:
Working on the principle that most RAF training was done in Canada I
enterd the Canadian Pacific 3612 into google and it came up with class
N2a.
Entering Canadian Pacific N2a and selecting images brings up many
examples of which this one.
Richard Leonard's Random Steam Photo Collection -- Canadian Pacific 2-8-0 3674
I wouldn't 100% say it is that as some details look a little different
but that could be class variations, anyway it's a starting point.
It looks like the City of Vancouver archives have an actual photo of
3612 but I can't gain access to it.