The following curious tale has belatedly come to light...
Apatura iris was discovered at the MOD's Porton Down, on the Hampshire / Wiltshire border, during a BC Dorset branch field meeting there on Sat 9th July 1995 - when a pair was found, in full copula, wings closed, on the excursion mini bus's front tyre!
Porton is arguably the best butterfly site in the UK (depending on how one interprets the term 'site'), consisting of 7000 acres of chalk downland and areas of plantation or older woodland. Sallows, however, are rather scarce (if my memory serves me well), though on my last visit there, in late May 2010, I felt that the place should just about be Purple, particularly .
But why a mating pair on a minibus front tyre? They normally mate high in trees (for 3 hrs 45 mins). There is one record from the 1990s of a mating pair being found low down on a very windy day, having presumably been blown out of the tree tops (Ashtead Common, Surrey). 9/7/1995 was cloudless and hot, and seemingly with a moderate - fresh NE wind.
They might have been blown out of the tree tops, or perhaps they had been flushed out of the canopy by a bird, or by another amorous male (or two) trying to muscle in (as happens with iris)? Or perhaps the female had spiralled down in classic Willmottian rejection mode, only to change her mind (the minx) and terminate her virginity? Or perhaps the male, in classic Hulmeian mode, was determined to thrust himself upon her irrespective, and duly had his way? Other theories are welcome.
Meanwhile, I spent that day in search of High Brown Fritillary in the Forest (and indeed, I may have seen a female there, flying through Shatterford Bottom car park - if not, then the last genuine New Forest adippe was a female seen by me at Matley Passage on 30th June 1992). In keeping with the entomological tradition in the Forest for hot July days, I stripped off and bathed sublimely in the cool of a deep gravel-bottomed pool along some stream way off any beaten track - only for a posse of French schoolgirls to appear from nowhere on mountain bikes, and Ooh La La me terribly from amongst the bracken fronds. What happened next cannot be revealed on this website, but it was Awesome.
This rather begs the question of what else was happening in the Purple Empire that day? (It wasn't a good Emperor year, though 1994 was).
I am grateful to Colin Nunn of BC Dorset (and formerly of Christ's Hospital school - another Purple Old Blue) for details and photo.