Bee on Knapweed

Probably a Cuckoo Bumblebee, probably on Common Knapweed.

https://www.lancswt.org.uk/blog/cuckoo-bee-nomad-bee-identification#:~:text=Vestal%20cuckoo%20bee%20(Bombus%20vestalis)%20Male%20vestal,side%20of%20the%20abdomen%2C%20above%20the%20tail.

https://wildflowerfinder.org.uk/Flowers/K/Knapweed(Common)/Knapweed(Common).htm