As an aside, it seems odd that a German company was making Whitworth spanners.
AFAIK, mainland Europe never used these threads (and the AF sizes for Whitworth and UNF are completely different). This sort of stuff (as used in Healeys, Morris Minors, etc. etc.) was often branded 'King Dick', BSA, or similar. Oh, and please don't try typing the first one into an internet search engine.