The lens board is wooden but the extensin piece to which the lens is attached is metal and looks like a standard issue part for this focal length. This is probably the best clue if anyone has one of these on an existing camera.
I can't remember where I read this but I was under the impression that Goerz stopped using mm as an indication of focal length after 1914 and switched to cm. I also have a Dogmar marked 15cm which was a further development of the Celor in the early 1920s.
I did at first think that this might have been used on an Anschutz Ango but the board is too large for this camera. Maybe a Contessa Klapp ? Anyone have one of these?