Basking insect

I pottered out into the garden in the early morning sunshine with the macro lens, wondering what I might find. The hellebores are fully open and were tempting, and the daffs are still looking good with golden trumpets. But I spotted this ..... whatever fly it is? ...... sunbathing on a leaf. It sat quite still for a while, allowing me to get closer, and started to wipe its head with its fore legs - was it washing it's face???
So if anyone can identify it I'd be interested to know.

This is the cleanest macro shot of an insect I have ever managed to take so I'm quite chuffed.