White-Letter Day

Yesterday was a Summer day. A summer day too, of course - and a hot and sunny one - but also a day on which Mrs N and I have the care of the entirely adorable granddaughter with the seasonal name, Summer.
 We had had the traditional tub of ice cream outside the café at Nonsuch Mansion (Tudor Gothick, Jeffrey Wyatville, 1802-6) and were strolling along the woodland path back towards Cheam Park when a nondescript little brown butterfly flew down and settled a few yards in front of us. What could that be? I wondered idly (it was very hot). The little brown butterfly folded its wings and at that point I believe I audibly gasped. There was no mistaking those underwings, that fine white streak ending in a semblance of the letter W, the orange-and-black border, the little tail springing from the hindwing... My friends, it was a White-Letter Hairstreak!
This news might not mean much to some (many?) of you, but let me assure you - to see a White-Letter Hairstreak like this, on the ground, settled (and this one settled not once but twice, with a little flight in between) is something that very rarely happens. This is a butterfly that is content to spend its life in the tree tops - elm-tree tops - feeding on honeydew, making the odd jerky little flight (more of a hop really), and seldom showing itself at all to the human world below. The last time I saw one - a faded specimen that seemed to have lost the will to live - was half a century ago.
 Being an elm-dependent species, the White-Letter Hairstreak took a hit when Dutch elm disease struck, but fought back very successfully, adapting to hybrid elms and wych elm in the absence of the good old English tree. It could in fact be one of our most abundant butterflies - and yet your chances of ever seeing one are very low indeed. Serious butterfly watchers resort to binoculars to get a glimpse of the White-Letter Hairstreak as it pursues its treetop life (which seems dangerously close to 'twitching' to me). In Partick Barkham's The Butterfly Isles he describes standing with a White-Letter enthusiast in a public park in Ponders End, feeling self-conscious as he trained a telescope on a couple of scruffy hybrid elms in the hope of getting a glimpse of underwing. He did.
 Vladimir Nabokov in Speak, Memory recalls, years after the event, a frustrating encounter with a White-Letter Hairstreak:
 'I remember one day when I warily brought my net close and closer to an uncommon Hairstreak that had daintily settled on a sprig. I could clearly see the white W on its chocolate-brown underside. Its wings were closed and the inferior ones were rubbing against each other in a curious circular motion - possibly producing some small, blithe crepitation pitched too high for a human ear to catch. I had long wanted that particular species and, when near enough, I struck. You have heard champion tennis players moan after muffing an easy shot... But that day nobody (except my older self) could see me shake out a piece of twig from an otherwise empty net and stare at a hole in the tartalan.'
 Truly an elusive butterfly to have escaped even the voracious net of Vladimir Vladimirovich.