Carrying badges reading "B & M Leitz" on the door and "Leitz" on the overarm, this 1950s "Leitz" miller is rare. A full and interesting description by the owner of a similar model can be found by searching on this web site
The background to the machine is a mystery: the Leitz company, founded in 1876, is best known to the general public for its cameras - but that was only part of its business for it also manufactured a very wide range of high-precision microscopes and other high-class optical devices, cinema projectors, precision coordinate measurement equipment including optical comparators and surveying equipment, drawing instruments, slide rules and even a range of small jig borers intended for the watch-making industry.
If the miller was bought-in from another maker. with Leitz badging applied. or built in-house is not known, though the latter seems unlikely given the huge number of specialist tasks involved in drawing up a design, making patterns, casting and machining - though, of course, not an impossible task for a talented an organisation.
If you have a machine tool by Leitz, the writer would be interested to hear about it..