This is a different hoverfly to the long hoverfly and the Melanostoma mellinum. It is a Marmalade Hoverfly because of the two moustache-shaped black bands on its abdomen. Some, but not all, have paler bands like this one, or even white bands. It is possibly the most common hoverfly in Britain. It can be found in gardens, parks and hedgerows and loves a sunny spot.
This tiny fly is almost definitely a Lesser Dung Fly, as it has clearly visible dark wing spots, one on each wing. There are many species of dung fly, and it is advisable to identify them with a microscope. However, I didn’t have one handy, so I am relying on the dark wing spots and let’s just say it’s a dung fly that is smaller and less yellow than the Yellow Dung Fly I saw before! They eat what you’d expect a dung fly to eat!