Nick, Canada (presumably due to their Commonwealth status) got all the "good" stuff from Standard and Triumph, such as the Triumph 1300 and (briefly) a Triumph-badged Standard Pennant. A few of the 1300s have made it into the US, but I've yet to see one (only heard rumors about same). I lucked into a Triumph Pennant bonnet badge a number of years ago, and that's the closest I've gotten to seeing one of those cars (although I do own a privately-imported Standard Pennant).
The Atlases fall into that "grey area" of cars brought in for evaluation and/or S-T employee use, or those brought in privately under the "Personal Export Delivery" scheme or similar (I also own a Herald 1200 Coupé brought in that way, since the 1200 Coupé body style was not sold in the US).