This was taken on some dill. Distinguishing the species is tricky for me as I am no expert and the patterns are not quite clear & I think that the body patterns sometimes vary within species (the yellow can join up more and indeed you can make out differences between these two now I come to notice it) but I would hazard that this is a pair of common Syrphus ribesii.
I wish them a long and happy relationship. They flew off still coupled which makes me wonder which one was doing the flying and which giving directions! Seriously though, how does that work?