at the edge of a wooded lake - heaving after dark with Daubenton's bats
No interactions present.
It's obviously a Ferdinandea and probably cuprea, but a specimen would be nice, to be certain it's not ruficornis, as it is quite dark. diptera.info is a really good site, but not everyone offering an ID is an expert on UK flies. Dipterists Forum is perhaps a better bet, for flies from the UK.
My Flickr photos...
I tried it yesterday without response then looked at the other observations and the quality of the pictures and the confidence levels, and it seemed those specimens had more obviously brassy abdomens. This was about the size of a big trivittatus, say, and the thoracic stripes seemed to fit. I tried it on diptera info without my suspected id and it came back as this..
.. but on that point, who are these good people? It doesn't seem as though I can tell whether it's an expert or someone having a good guess, in fact I've unsubscribed from the sawfly forum because of completely opposing views between someone there I don't know and an ispot expert whom I know from here.. that and loads of emails about everyone else's stuff.
latest pics and diptera videos
That may be a good reason to go for Dipterists Forum, as the people commenting there are reliable dipterists, often leaders in their field...highly recommended, and if you are not already a member, you should be!
Lat/Lng: 51.9662, -1.9271
OS grid ref: SP051297