I took this photo of the Hoverfly Helophilus pendulus last September. Hoverflies seem to enjoy the sunshine and can often be found sunbathing. I believe this is the female. This species which is often found in gardens can be identified by its yellow face and black stripe between the eyes and the distinctive longitudinal stripes on its thorax.
280+ species of hoverfly have been found in the British Isles to date although new species are being discovered each year. The adults are not particularly long-lived surviving on average for just a few weeks, so enjoy them while you can. Hoverflies are harmless, and although wasp-like in appearance do not bite or sting. In fact in many species the larvae are voracious predators of aphids and therefore should be regarded by gardeners as their friends.
For an illustrated guide I can recommend the recently published Britain’s Hoverflies by Stuart Ball and Roger Morris.