Hello Marcus, I just found this old thread. My uncle gave me a Zeiss Ikon Trona 212 at Christmas. It was bought new by my grandfather, we think in about 1926, from James A Sinclair of Whitehall, London.
Only two holders are with the camera, one for a single glass plate, and one that I think is a pack-film holder. I wondered if you had any idea where I could get more plate holders from? The one I have has the number 760/14 stamped on it - is this the same type your camera takes? It seems quarter plate holders are quite rare.
I'm hoping to find time to test the camera out with paper negatives soon. Have you any examples of your work in the gallery?
Ian