Black and yellow hoverfly on Gorse.
No interactions present.
The wings are rather obscuring the pattern of the abdomen, but I think you are right. There are others with a similar pattern on the abdomen, like Parasyrphus and some Eupeodes, so a bit of caution is required.
My Flickr photos...
Lat/Lng: 51.359111, 0.036137
OS grid ref: TQ418641