Has yellow stripes on head but not very clear probably due to fading or still being soaked in alcohol?
No interactions present.
Perhaps pendulus, as hind tibia appears quite pale, but I don't think it is a certain ID, bearing in mind the poor condition of the specimen. Yellow stripes on head are not a specific ID criterion.
My Flickr photos...
Dry the specimen out for a few minutes and stripes, etc, will re-appear. It is very difficult to ID hoverflies when wet (ground beetles, etc too) as many identification characters disappear (colour patterns, shimmer stripes, setae positions, etc). With pitfall or Malaise trap material I always dry out certain invert groups (briefly) before identification. Otherwise very dubious dets!
BMIG website: www.bmig.org.uk (centipedes, millipedes & woodlice)
BMIG Newsletters ~ www.bmig.org.uk/view/resource/bmig-newsletter
BMIG Bulletins ~ www.bmig.org.uk/view/resource/bmig-bulletin
Lat/Lng: 51.8011, -1.4091
OS grid ref: SP408115