Thought this was a rather striking insect and have no idea what it is,on Nettle's on old compost heap.
No interactions present.
so you force me to get my specimens out. I agree, head marking and eye-occiput length suggest chlorosoma. However, these features also fit male viridis, palest ones v like chlorosoma.
Is it a common fly as I have never seen them before.
Sorry about that David :-) We could just go with Rhogogaster sp.
Fenwickfield - they seem to be fairly common. A good but brief description is at http://www.naturespot.co.uk/species/rhogogaster-chlorosoma (or change the last word of the url to see the other species). This site focuses on Leicestershire and Rutland but also refers to all of the UK.
It is nice to know what it is but I also like to read up on the subject so I can learn and hopefully recognise future finds,will look at the site you have suggested.
Lat/Lng: 55.05731, -2.23248
OS grid ref: NY852736