Back in 1957 there was an article in the Numismatist that condemned all the open topped stamps as being counterfeit. Back then almost any shaped stamp was accepted but a flood of late dates that were impossible caused that re-evaluation. Many stamps condemned at that time were asymmetric with short or vertical arcs.
I do not have access to any of my reference books but I wonder if there is a legitimate basis for considering the crude asymmetric open top stamps to genuine?
That was the reason for the post in the first place.