Hoverfly

Not been feeling 100% today so not achieved a great deal. I was on fish feeding duties at the Butterfly House today and took my camera with the intention of getting a nice blip of a newly emerged butterfly. 
However, it was really cold in there and most of the butterflies were roosting under leaves and on the netting which was a bit irritating. Even after I put the heating on and it warmed up a bit, there was little action. 
I did see this little insect hovering about a couple of feet in front of me so set about trying to capture it. It's not so easy when it's so small and took a while. I imagine it is some sort of hoverfly but I have no clue as to which species it is.