I purchased it from a fellow I met through work, actually. The story is that his father, while serving with the 2nd Canadian Infantry Division (he mentionned tanks, so I imagine either the VIII Recconnaisance Regiment, or he actually meant the 2nd Independent Armored Brigade), traded a Luger he'd taken off of a dead German to an American paratrooper for it. He apparently carried it around for the war and got ammo whenever they passed American supply dumps. He then had a Colonel he was friendly with smuggle it home in his bags for him, as he figured they wouldn't be searched.
Now, like most experienced collectors, I tend to take those stories with more than one grain of salt, but the fact this this gun shows none of the immediate postwar upgrades (adjustable sight, bayonet lug) and had never been rebuilt makes me think theres at least the possibility there's some truth to it. After the time I've spent in the army I have trouble imagining a Canadian soldier getting away with carrying a non-standard weapon like that, but I think that Dad maybe did bring it home from the war.