Summer flowers - knapweed

Insects always seem to be attracted to knapweed (or hardheads) and this one obliged by landing just before I pressed the shutter. Seen at Williamthorpe Ponds, a reserve and industrial park on the site of a former colliery.

After on-line research and comparing visually from images available, I am fairly certain this is a hoverfly, Chrysotoxum festivum.