Hello! Yes BGS had traditional uniform, on a Berlin Museum website I have found this picture of a BGS general cap with gold piping as in WW2 general...
In my view this is an Arts and Crafts style box, that predates WW2 by at least 20 years. And I think it is odd that this workshop has not identified...
Ps it shows true signs of wear, especially on the ring loop. The darker spots for example between the letters are dirt, that should be gone, as soon...