Many thanks. Had actually located it independently also. And found inter alia, for those interested

"It is of a distinctive model, with rectangular buttons, suggesting that it was made by the mid-19th century Chemnitz maker Carl Friedrich Pirner".

Wowie.   Something that has exercised me for years. So I get around to put up a query here. Answered in full in less than ¼-hr.

Mudcat strikes again!

Profound thanks again, Peter

≈Michael≈