Not sure what this bird is. Possibly winter black guillemot or a slavonian grebe.
Took some of the photos through a telescope.
No interactions present.
It.s a Common Gullemot in Winter plumage
This is a winter plumage Common Guillemot. Black Guillemot would have a paler back and a large white spot on the wing (with black spots on, if immature). Slavonian Grebe would be much smaller.
My Flickr photos...
Lat/Lng: 50.6176, -3.4243
OS grid ref: SX993807