A small unidentified fly rests on an rusty, iron handrail.
I took Victor‘s advice and went with a “less (color management) is more” approach, by turning off the color management mode in GIMP. (For GIMP 2.8 in OS X, go to the menu Gimp –> Preferences –> Color Management (in the sidebar) –> Mode of Operation –> select “No color management.”) I then discovered rather serendipitously through my troubleshooting internet searching that Nikon has a new photo management/NEF (RAW) editor — well, new to me — and it is called Nikon Capture NX-D. Well, hot dang. I downloaded that toute de suite, installed and what do you know? My photos now look the same after I convert them to Tiff files, which was not the case when I was using Nikon View NX2. Will wonders never cease. All of which reminds me, now that my blood pressure is down again, that I need to uninstall some software.
BugPhoto.net 
With 150,000 species worldwide, 6,900 in the UK alone, diptera is a hell of an insect order to get to grips with. As such there are a lot of ‘unidentified’ flies. However, with this kind of detail where you can clearly see the bi-colored legs I reckon you could get an ID.
Many of my “unidentifieds'” could also be of the “unambitious” tribe of my identifications (that’s a personal classification, ha). I did notice the bi-colored legs too; if the spirit moves me, I’ll have to run a search through BugGuide.net.
Great fly!
Thanks!