What a wonderfully clear explanation! Thank you Mauriz. I have spent the day thinking about it all. Without the imagery I would have been lost!

Your analysis makes a great deal of sense, and I think is probably correct.

I wonder if the image Dave gave a link to and the information came originally from an auction catalogue? But where and when is the question.

PS. I was delighted to learn more about the Empresses of Austria. Knowledge of them is one of my many weak spots. Juscha and Mauriz have expanded my knowledge considerably.