A wasp-mimic Syrphid, one of the 'difficult five'. In flight it looks just like a pub garden wasp but on settling shows it's a hoverfly
No interactions present.
The scutellum colour is not important, as far as I know. However, the antennae suggest cautum, as the first section is shorter than the second, and the third is about the same as the first and second together.
My Flickr photos...
Lat/Lng: 51.5616, -0.0385
OS grid ref: TQ360865