I'm hopeful that someone with better knowledge of butterfly behaviour can tell me what's going on here. I think these two are going through a mating ritual. The female (below in this photo) is sitting quite still on the grass with her wings flat and abdomen raised perpendicular to the ground. The male was repeatedly bombarding her from above. I was trying to photograph them with quite a high shutter speed but because his "attacks" tended to buffet her, I lost focus 95% of the time. This was the best I could do. They tumbled off over a hedgerow before I could come to any certain conclusions about what was going on. So, er, are they preparing to mate? Or is something else going on?