Ah, one thing I never saw was an N at the beginning, only R, K, even X!
But thanks for that, and the links, both.
I did wonder about Czech, originally, because of the colours but there seem to have been dozens of French companies making very similar lamps throughout the last century - and probably into this one.
The newspaper packing was blurry mush, nothing to yield from it.
The lamp came from a house clearance in Copenhagen last year, possibly even the year before. It's been sat in the attic in pieces for a while until I got around to bringing it back to life with fittings that fit and wiring less likely to kill you!
I'll see if Nouhaud can yield anything further. Thanks again.