I've known better Purple Hairstreak years, most notably 1976 which was probably an order of magnitude greater - they roamed the oak woodland edges in loose swarms.
Although most active during the evenings, when they conduct their courtship and mating, and largely quiescent during the heat of the afternoon, this July they have been coming down to visit bramble and Creeping Thistle flowers, as they do in drought summers - it's just that we haven't had a drought July since 2006 and 2003.
Alongside His Imperial Majesty, the Purple Emperor, this hairstreak seldom visits flowers. Here's one feeding on bramble -
Here's a better one on Creeping Thistle -
And one feeding below a faded Creeping Thistle flower, I'm not sure on what precisely... -
They've also been probing around for moisture in damp grasses, first thing in the morning (which they did prolifically in early July 1976) -
Best of all are the Purple Hairstreak Ash feeder trees - if you can find one. I found one at Knepp late on. Here, at least 20 quercus were in view, probing around on next year's ash buds and, seemingly, feeding on lenticels (secretion pores) along the stems -
They have remarkably short tongues.
Very much a candidate for Butterfly of the Year...