High diver - my first

Whatever it is. I am hoping an expert can see enough of it to tell me. I looked at my one and only insect book and thought maybe a robber fly? I don't think it's tail is long enough for a dragon fly. The tail is hidden a wee bit by the coprosma leaf it is sitting on sunning itself. I was thrilled to see it let alone get a half decent photo of it about 4 metres up.