I hadn't even clicked that it was a hoverfly until I pointed the camera on it, but before I could do anything meaningful it buggered off never to be seen again. Anyway, it's a Pipiza sp. and it's a female. It is quite likely Pipiza noctiluca but there are several similar species. Even P. noctiluca is likely to be worked into a number of new species.
I also spotted and snapped another garden visitor that I don't recall seeing here before, and yet again another that can't really be reliably identified from a photo ....
Anthomyia sp. - quite likely A. procellaris
More certain, but less attractive, was this big fat Tree Bumblebee on my alliums