My caterpillar has turned into a chrysalis. can't wait to see what happens next.
No interactions present.
I sure hope it is a Nymphalidae
as these look like nice butterflys. I found the caterpillar on the nettles, there are millions of them round here. I have the chrysalis at home and will see what it turns into and put the pictures on when it emerges. This could be Argynnis paphia as that looks like the caterpillar I found although the Nymphaliis io and the Nymphaliis urticae both feed on nettles the others seem to feed on violets.
It doesn't really look a Silver-washed Fritillary pupa and, as you say, their larvae feed on violets. Peacock larvae are black, so quite different from S-wFs.
My best guess is that it's a Small Tortoiseshell, but I wouldn't put money on it.
With luck, you'll find out for sure in a couple of weeks. :)
Lat/Lng: 52.9063, -2.1606
OS grid ref: SJ892343