That's a good question, and partially why I asked this.
There's high end guns like the bottom one here of Fug's, which definitely might be "Extra finish on stock". It surely has extra coats, but is it just extra finish? Or might this be an example of the London Finish?
But I've seen a few that seem as though they just have a "deeper" or "thicker" finish than normal. This 1899 SR for example. But maybe this one is just "pristine"?