Pallopteridae (flutter flies/trembling-winged flies)

Variously listed as flutter flies (e.g. Falk's Flickr collection), trembling-winged flies (e.g. NatureSpot), long-winged flies (Brock's Britain's insects) or (with other families) picture-winged flies (Brock's Insects of Britain and Ireland).

At least one more to follow in due course...

Four-spotted Flutter Fly Palloptera umbellatarum