European Crane fly, Tipula sp., female. A recently introduced fly.
I saw this fly from a distance, landing among the grasses. As soon as she stopped moving, she became invisible, except for the two iridescent wings. The body matched the dead stems around it. I got as close as I could without standing in a creek, to take the photo with flash, which made her stand out. Her legs change colour according to the direction of the light, so that they seem to be random pieces, not connected; another aid to camouflage.
She's smaller, and a much lighter shade than the big brown ones that visit me at home.