I'm inclined to think you're right, Paul, but the honest truth is that I just don't know -
pales in particular is extremely variable. What I do know is that both species are common upland butterflies in my region and the females, which fly from mid-July onwards, are quite distinctive and unmistakable. Sometimes the males are distinctive in the field, particularly when you get a more macular, small, male
pales, or a large, bright orange, superlinear, male
napaea, but often, through laziness, I just call
Boloria and confirm the species when a female comes along. Quite often I'm really looking for something else, and the
Boloria are zooming around - so I don't chase them. It's a project for next year, perhaps!!
I remember the Simplon butterfly - it was one of two posing together when we found them. I have photos too, of one of them, and despite the uncontrasting undersides I am happy to call them
pales. By way of contrast, I am quite sure this one, photographed at the other site, is
napaea:
I will keep investigating, but if you (or anyone else) come up with something you think is definitive, let me know! I find the Lafranchis method quite useless - it doesn't even seem to work for the pictures in his own books, unless I'm misinterpreting it somehow!! When something definitive is found, apart from size, I think it might well be on the underside.
To be continued...