Thanks for all the comments guys

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Ernie, those clouds were in the distance, above us and the Hairstreak was relatively bright. Had it been that cloudy there's no way I'd have been able to get anything sharp!
5th September, back out at last
It feels like an age since I last had the chance to get out, indeed a whole new season has descended since I was last chasing butterflies! Anyway it was a tossup between Box Hill and/or Denbies or Bookham. I had a few things to do in the morning so I couldn’t get going until quite late on so I plumped for Bookham, figuring I’d get there in time for the golden hours of Hairstreak activity. On arrival there was a lot of activity from the local Specklies, mostly now ghostly versions of their former selves.
I found a few Coppers as I wandered the hedgerows, all males as far as I could tell and mostly fresh indicating a new brood is just starting to emerge. I watched a couple of these fresh ones have a minor scuffle before one settled, closely followed by the second close by, whereupon the second one sidled up close. Perhaps he practicing his moves for when the females appear?
In amongst the ghostly Specklies, the occasional fresh specimen stuck out like a sore thumb, looking especially dark.
A few more circuits of the Hairstreak hotspots threw up much the same collection of butterflies, but no Hairstreaks.
I decided to have a wander into the wood to see if anything was around there, perhaps a second gen White Admiral? Nothing except more Specklies and hordes of Darter Dragonflies. Close inspection found both Common and Ruddy Darters, distinguishable by the pale longitudinal stripes on the legs of the Common Darters compared to the solid black of the Ruddy Darters.
On the return I checked on the trio of Purple Hairstreak eggs near the car park, finding the first two healthy but the third one had clearly been parasitized at some point and is now just an empty shell with a hole in it.
Another couple of circuits of the hedgerow still came up blank on the Hairstreak front but I come across an unusual fly I have never seen before. can't find anything like it on the interweb either
More Coppers and a few Fresh Small Heath started to appear mid-afternoon, the Heaths looking more normal than the sandy coloured ones that were appearing during the height of the summers dry spell.
I ended the afternoon looking round a patch of Blackthorn where both Pauline and I had found several larvae earlier in the season but to no avail. I did find a Common Blue posing, a couple of flies having a standoff and a rather nice dusky
caeruleopunctata to finish the day off.
No target species but certainly not a write off

!