Feeding on Knapweed. Common.
No identification made yet.
No interactions present.
Orange/yellow rear underpart. Thought it might be a leaf cutter or a carder bee.
I agree that it is a solitary bee, and that there seems to be a hint of orange hairs under the abdomen, which would suggest a leafcutter bee or (perhaps more likely given what appears to be its small size) one of the mason bees in genus Osmia. Can't quite see enough detail to say anything definite though.
Entomologist and biological recorder
Lat/Lng: 51.7365, 0.4686
OS grid ref: TL705070