Your correspondent was recently part of a National Post article about erotica (aka porn) held at Library and Archives Canada. And here is a link to a LAC web site about Canadian pulp. The article showcases two Canadian paperbacks - Harlequin 1 from Winnipeg's Harlequin Books and Crow 21 from Toronto's Alval Publishers.
I've been collecting the White Circle series from Toronto Publisher Wm. Collins & Sons Co. Canada for about nine years. I have all but two first printings but remain unsure how many other printings I'm missing. For instance I just came across one of my favourite reprints from 1943/44 that I didn't know existed. These are reprints where Collins changed the colour of the covers but kept the design. In this case, like a few others, the printings can't be distinguished. The only diffference, aside from the colours, is an odd loop at the bottom of the "R" in "Whispering" on the red/blue version. At this point there is only one of these reprints that I know I'm missing. Could be others.