This Fly is in a huge family of very simlar flies. This one I think is Empis Opaca - not to be confused with Empis Tessellata which has black thighs rather than red-brown! They live in hedgerows and take nectar from flowers. However they all get their common name 'Dagger Fly' from the fact they also predate on other flies. They do this by spearing them with their rigid downward-pointing proboscis (which you can just see in the photo).