The best hope of dating an old German piano is to get your tuner to remove the action (the working parts of the notes) and look for the action makers' name and number on the back of it. My Names page
mentions what seem to be bogus German names on genuinely German pianos sold in Scotland, and I wonder if this one from Machell is another example. Certainly, Wittig pianos were sold by Thomson, Glasgow but also Harston, Liverpool.
Email via my website.
If you find old references or links on this site to pianogen.org, they should refer to pianohistory.info