I suppose it could be a shako from a musician, police, fire dept, or even Beamter. Everything looks like it "fits", looks like it belongs. Nothing appears to be added or modified. I'll have to do more research before I consider buying it, and I'll have to find out what it actually is!
John
P.S. I have looked everywhere and can find no information on this. There is one like it offered on Ioffer, but it looks wrong, sort of a cheap copy of the one I'm looking at and the one pictured above. The one I'm looking at looks, feels, and smells original --- but original what?? I have decided to pass.