Now we’re in the kingdom of the ‘true flies’, the Diptera. We don’t take specimens so all we have is the photo and the internet. To the eye they look like muscid flies (the ‘house fly’ family) but there are so many flies and they are so hard to tell apart. To be sure you have a house fly rather than a root-maggot fly, for instance, you need to count the hairs on its back and I really don’t have the patience, or the eyesight.
Our best guess though is Thricops diaphanus, a common species all over the British Isles. It is usually seen from late summer to late autumn because the larvae depend on mushrooms. They don’t actually feed on mushrooms, but they hunt for other insect larvae inside mushrooms. Its only late June but its been so wet that there are fungi around already, in which case maybe it is TD and they will be around to amuse us with their happy faces and affectionate antics for a few months yet.
Do you want to know a horrid fly-fact? According to Garden Safari, Lucilia bufonivora (looks like a Greenbottle) deposits its eggs in the nose of a toad. The toad is than eaten from within. There’s a ghastly YouTube video if you’ve a strong stomach but don’t watch it before dinner.