One last thing. The stamp on the right of your scan is a rotary printed stamp. I copied and shifted your #552 next to it:

The horizontal perfs match but the vertical perfs don't. That combined with the design showing through the back means that it is a 1922 series that is perf 11 x 10.5. This means that it has to be a "Tall" rotary printing. If you place it next to your #552 you can see the design size difference. You can now use it as a reference to help identify "Tall" rotary stamps.