www.ukbutterflies.co.uk

Went for a walk on Lydlinch Common (North Dorset) on Thursday 8th Aug - just killing time - and saw a Valesina SWF - just as the entry on this site describes, looking in flight like an overgrown Ringlet. Certainly was not expecting to see this especially on a fairly dull overcast afternoon when the only things flying were a few optimistic Painted Ladies. Will be returning to see if I see more SWF esp Valesina variation

Hope you're lucky, Innes Henry. Valezinas are exceptionally beautiful.

Butterflies, the most studied of Insects.
Valezina was thought by one, to be a genetic variety that occurred, because the SWF butterfly was forming relatively smaller, isolated populations in the South of the United Kingdom.
Because butterflies complete their Life cycle in just one year, their ability to evolve different genetic traits might happen faster than in those in species found higher up a food chain, where individuals live for much longer.
The 'small island" population of Silver-washed Fritillary at Bookham Common did not have a very high percentage of "Valezina" (I did not see or record any 2013-2015, but saw many females). Others had also, not seen it there.

"valezina, which is rare in Surrey but can be up to 15% of the population in other southern counties such as Hampshire and Wiltshire" Reference -Butterflies of Surrey -Revisited by Ken Willmott

"The great lepidopterist F. W. Frohawk was so enamoured by this variant that he named the youngest of his three daughters Valezina" -Reference The Butterflies of Sussex
"The dusky bronze-green form of the butterfly is controlled by a gene which is only expressed in the female sex. Perhaps surprisingly, given the relative rarity of valezina, at least in Sussex, this gene is dominant, so it's presence should be reflected more widely in the adult population"
-Reference The Butterflies of Sussex
Reasons were then given for strong natural selective pressures acting against the valezina SWF but my thought was (and some people might not thank me for it), that some breeders might have had another selection process, because of it's beauty.
My preference for someone in authority starting a new Woodland colony of SWF in the United Kingdom, would have been for one to legally, take some SWF individuals where the species could be found in genetic strength (like for example, a Swedish colony that had not been so isolated) and mix with some individuals from a United Kingdom colony, if they were still all using the same or very similar caterpillar food plant.

Kind Regards.