I saw this insect at Wash Brook Nature Reserve. Looking on the species gallery I think it might be a Syrphus Ribesil but I'mnot sure.
I'm fairly new to insects, so any advice is welcome.
It's a female Syrphus sp. - can't tell which species from that photo - S. ribesii has hind femora that are nearly all yellow, but we can't see them here.