A first I thought they were bees but, looking closer at the photos (click to enlarge), you can see that these insects don’t have the long, curved antennae typical of bees. If (as I think they are) these are hoverflies the fine, wispy hairs that look a bit like antennae are in fact aristae and the antennae are the little, dark club shaped objects next to them.
I know bees have two pairs of wings while hoverflies (being flies) only have one pair plus a pair of stabilizing halteres, but bees have a crafty way of hiding one pair of wings behind the other so ‘count the wings and divide by two’ isn’t very reliable. It’s not at all scientific but these look like flies’ eyes to me. Any other aids to identification (which don’t involve counting the hairs behind the insect’s knees) gratefully received.
The hellebore flowers in the first photo, though the most attractive to human eyes, were not attracting any insects, whether hoverflies or bees. These flowers had already set seed and the stamens were ready to drop so there’s no nectar on offer here.