Purple Emperor

You can wait a long time to see one of these on the ground, even if you know where they live and know the right dates for their emergence. I was worried for this one since it settled on some dog poo right beside a popular horse riding spot. I'd found one a couple of days earlier that was dying. It looked to have been trampled. Once they're settled on a favourite source of minerals, they're hard to prise off. They're not put off by people, dogs or horses. It was so preoccupied I could take a picture with the phone.

The weather conditions were far from ideal but it was warming up a little and there was brightness through the cloud. Even so, I wouldn't have seen this had I not turned around and spotted it descending from the trees. I saw another later on but that flew off. 

The purple colour (which is more of a blue) is only visible at certain angles as you can see from the extras. This is a male gathering strength for the territorial battles ahead when the females emerge. These really are butterflies with attitude. They'll even fight with birds to protect their breeding spots high up in favoured oak trees. Now's the time if you want to picture one close up. After mid-July they'll be in the tops of the trees. This was at Bookham Common.

I've just checked back out of interest and the one I saw last year was two days later.