Superfly

I think it's a Drone-Fly, or possibly a Myathropa Florae. The Collins Complete Guide to British Insects (that's right - I own such a thing) tells us that the Drone-Fly larva, "known as the rat-tailed maggot, lives in stagnant water". Lovely.

Blipped on my birthday walk in Belhaven. Now sitting with a bottle of Fursty Ferret while the wife cooks the Sunday Roast. Excellent.