>>The outer was clear glass, then was a solid board which could be closed to block out sun light, and innermost was a stained glass panel. Or was is the stained glass panel was in the middle? Either way, the two inner ones could be slid (down) out of sight while the outer - clear glass - panel slid up.<<
Daniel, the shudder, as always, was most likely on the inside, with the stained glass in the center. How could a shudder be closed if it had been in the middle? The stained glass panel, if on the inside, would have to be lifted first. That's too inconvenient. It would obviously make better sense to fit the shudder on the insider where it could just simply be lowered or raised and/or adjusted if necessary.
By the way, where did you find this information? Would it be noted on the blueprints? Most likely, I suppose, as the blueprints naturally provided a detailed guide for construction, so such information would, of course, have to be. I just wondered.
Take care