JDW,
The gun in the picture looks exactly like my FWE Ideal. Very shiny, obviously polished very well before engraving and casehardening. Mine is not plated for sure. Nickel 80 yrs old will still be yellow. I can't conclusively tell it's not yellow in the pics, but it sure looks like bare polished casehardened steel just like my gun. Shiny finish doesn't mean plating necessarily. Nor does a plated surface necessarily end up shiny. Shiny, whether plated or not requires polishing. With plating, it can be done before somewhat and if a really mirror finish is needed, polishing after plating may be needed. I'm still of the opinion yours is not plated.