As usual, Jock makes several good points. I like your use of Pantheon, OC, and it brings to mind the problem we keep bumping into. Just as the Romans and the Greeks had similar deities with different names, Kinloch Anderson and their competitors can barely agree that the garment below the waist is a kilt- after that, proprietary nomenclature takes over.

Another thread discusses whether or not the Argyll is sufficiently formal for black tie wear, with interesting points raised about lapel facings and somewhere we see and hear about different lapel shapes, too. It is easy to assume that the notched lapel is the only current lapel option for single breasted suits, or that double breasted suits will always have peaked ones. In my closet today are several single breasted peak lapel suits. They are not exactly commonplace, but they have had their followers throughout the 20th century. The Nehru jacket has a small, but persistent niche even in western menswear ( Euro-American western, not Cowboy western) and somewhere, I am sure a very proper stylish gent is wearing a suit with two rows of buttons and notched lapels- like a US navy Pea Coat. I even have a hunting jacket, off the rack since the Viet Nam war or thereabouts, with a shawl collar.

My point is that all of these variations turn up repeatedly over the last couple of hundred years. And they never quite go away.

I do not dispute anything said above about the jacket in question, but I don't know that lapel shape or even closure is going to be enough to say "This is a duck" or "this is a beaver". Shall we call it the Platypus Doublet?