I have seen lots of these this year, I believe it might be a Pipiza. I have ruled out some species but cannot tie it down at all.
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Ophrys, thanks for that, it's another one I'm unfamiliar with but noted for the future.
Chris Brooks - www.dragonfly-images.co.uk
My Flickr site - www.flickr.com/photos/ceb1298
Looking again at the face, it may not be hairy...difficult to tell. It could perhaps be albitarsis/ranunculi, then. Really, trying to do most Cheilosia from a picture is rather a waste of time!
My Flickr photos...
Lat/Lng: 51.2, -1.0
OS grid ref: SU7451