Nice catch. It was taken from a picture of Kaiser Wilhelm and Tsar Nicholas II. I assumed that Wilhelm was wearing the pointy hat, but they had actually swapped uniforms for the photo. Changed it to a picture of Otto von Bismarck.
I'm curious as to which other Bach works would be more familiar than the Brandenburg Concertos... Apart, maybe, from Well Tempered Clavier, I don't really see. Maybe Toccata and Fugue?
Tried Hansa 100 times.... the same with book printing :(