That's interesting to know, Roger.
Believe it or not, the Camberwell beauties were still on the wing today, 13th June, when Matt and I saw two different individuals (at widely separated sites). Here's one of them, perched most unhelpfully on the top of a post well above head height!!
I presume he (or she) can't have emerged later than August last year (I normally see fresh ones in July) and so he (or she) has probably been around ten months at least by now. What a marvellous life-span for a butterfy!
The summer butterflies are creeping out now, but many of the spring species are still around too, albeit tatty and in diminishing numbers. This 'cusp' helped us to 65 species today (if I haven't left anything out of my accounting), despite a general feeling we both had that butterflies were not numerous!!
Guy
EDIT
I've just checked and my previous record seems to be this very tattered CB I photographed on 10th June 2006:
