Comma butterfly at rest

I'm rather thrilled to have captured this shot today. My camera isn't really up to taking decent close-ups but I persist in trying.
As I walked down the lane with the dog this afternoon I saw a flicker of orange coming to rest on the bank and was close enough to see where, otherwise this elaborately camouflaged butterfly would have been invisible, so exactly does it resemble a ragged, withered leaf. (Its caterpillars are also camouflaged - as bird droppings)
Polygonia c-album is interesting in a number of ways. Its Latin name refers to the white 'c' or comma mark on the underside of its wings. In contrast to most other British butterflies its range is extending and it is more frequently seen than it used to be. It has two distinct forms depending on which side of the midsummer solstice the butterflies emerge from pupation. Those that emerge while the days are lengthening are lighter coloured and they go on to breed before the winter. Those that mature when the days are decreasing in length are darker in colour and will hibernate before breeding in the spring. A sort of insurance policy that gives the comma two cracks of the whip at reproduction.
I reckon this is the dark form and with luck it will be back laying eggs on my many nettles come the spring.