The Max Frankel Yale and the Buffalo NY key Pete added have coined bows with raised markings like factory originals. They are not incised or engraved but factory coined from dies which indicates investment in tooling costs and the inevitable quantities involved. Probably a lot more expensive back then compared to having the same made today.
Nowadays usually done on a one-off tooling charge and/or higher minimum order quantities, the numbers involved suggests there would have been a lot more of those around back at the time. Over time many will have been lost and discarded as locks become repaired or replaced.
Its common practice over here and presumably still so, your side of the pond, for locksmiths to have their most frequently used blanks made with company name and phone number. We had quite a few done and they proved an effective source of repeat key cutting and business as Pete suggested.
