http://laws.justice.gc.ca/en/C-42/38355.html
I thought that we really ought to get back to the source of Canadian copyright legislation and so I searched and found it! Thanks to Clive for prompting me to get the definitive answer.
Basically, it seems that Crown Copyright is 50 years, so WW2 photos and post-war to Korea are out-of-coyright now.
Corporations and those photos/works that corporations paid for and therefore own the copyright, have a 50-year limit.
Where the photographer is not known it is 50 years for publications and 75 for say photos but where the photographer is known then it is Life + 50 or 75 as the case may be.
I read this, and am willing to be corrected, that if there is say a veteran taking a photo then copyright would still subsist. If it was a paid-for photo then as it would be expected that the photo copyright would belong to a corporation, 50 years applies. An official war photgraph would be out-of-copyright.
I am putting forward the suggestion that all GM of Canada, Chrysler, Ford, OF CANADA etc. official photos are out of copyright even if they were Crown Copyright originally.