I've just got a POW postcard from an A L Stranger who I believe is H42308 (he's the only A L Stranger I can see as a POW) of the Edmonton Regiment, the bit that's confusing me is the postcard is dated 9th April 1941, but from what I can see they didn't see action until a Company took part in the Spitzbergen action in August 41, so not sure how he was captured (assuming its the same man).
The Loyal Edmonton Regiment and the Princess Patricia's Canadian Light Infantry were supposed to go to Norway, but that was cancelled. However in the same paragraph in Col. Stacey's book he mentions Order of Detail No. 1 where some anti-aircraft Lewis gunners in March 1940 were lent out to serve on North Sea trawlers as protection. Stacey implies that that they came from these regiments. However, I could be reading more into this than is there. See p259 of Six Years of War Volume I. So maybe your man served as a AA gunner on a ship that was sunk and he was taken POW.