A bee but I don't know what species.
No interactions present.
That's interesting that it's a fly not a bee. I know there are lots of differences but is there a general give-away sign to distinguish a fly from a bee?
I'm sure someone else will add more but the antennae are a good start. Bees tend to have long often jointed antennae, flies have shorter and much less obvious ones.
Chris Brooks - www.dragonfly-images.co.uk
My Flickr site - www.flickr.com/photos/ceb1298
Lat/Lng: 51.9, 1.3
OS grid ref: TM3034