A 6 inch long example of this wrench appeared as online auction offering from an Australian seller. The markings were "BECHERS D.R.P. 105813 // SCHLÜSSELKÖNIG."
Corresponding British patent GB-189908999 (8999 of 1899) was granted to Carl Becher (listing only from "Abridgments of Specifications" -- the patent is not in ESPACENET).