It looks like it says
Bleckmann
Boligen
Germany
No idea on the age, google was useless again.

Hello, Oldgoaly. Try looking at jeweler's die stock. Regards, Lou

Actually, for a jeweler , it would be called a screw plate, thread sizes are usually very small, and I have never seen an adjustable one.

Thanks Lou!
It's one of those things in the box with a change gear set, and it is trying to rust! 
So time to find a good place for it so no more rust!

Had one of those in my hand yesterday but it was missing the thumbscrew.

Try Soligen, Germany.
These came in a bunch of different sizes. Some quite a bit larger and also smaller.
I'm not familiar with the manufacturer.

Mike

Funny you should mention a missing thumbscrew.  I was at a sale on Thursday and scored an old Craftsman tool box with some screwdrivers (including a cool perfect handle type) AND a nice Spofford type brace.  Beautiful cupped rosewood knob and a tight pewter ring handle.
But it was missing the thumbscrew. 
I poked around in the box, and lo and behold, came across a smallish pressed steel clamp with exactly the correct thread size and (almost) the correct thumbscrew.
The clamp is no more.  But the brace is very nice.

Hello, Mike. You got me thinking, is it Solingen? Seems like I have seen that name on knives/straight razors. Regards, Lou

Lou, you are quite correct, I left out the "n". Should be Solingen. Thanks for pointing it out.

Mike

Looks like Bleckmann made some interesting things!
Oh somewhere around here there are a few brass "thumbscrews" I've cast in brass for old stuff. Over the years I've used most of them up. My favorite one was "mickey mouse" ears that are hollow ears.
We should have a "thumbscrew thread"