I'm familiar with the classic Banded demoiselle damselfly, that does exactly what it says on the tin – i.e. it's banded, with massive dark blotches on the wings and electric blue body. It really catches the eye. The one above is a female however (I believe) and looks rather different. It's quite striking in its own way however and dare I say I was surprised when I looked it up to find that there is such a thing as an Emerald damselfly but that this isn't it. How much more emerald can you get?
There were the more obvious males around too, which I think helps confirm my identification. Unfortunately they wouldn't pose as nicely for me, but I think this is quite an arty and unusual shot and you can still just about see the dark patches on the wings…