After some further digging and help from an expert, I now believe this to be a Tufted Duck.
No interactions present.
The bill looks a bit blunt for a Guillemot; similarly it is unusual for a guillemot still to be in summer plumage - in winter it usuallly has a white throat and chin.
Do you have any additional photos / obervations, particuarly on size.
I've posted another photo, pretty similar to the first but with a Wigeon for size comparison.
I n ow believe this to be a Tufted Duck,what do you think?
After further digging and suggestions from a couple of birding friends, i now believe it to be a tufted duck.
Lat/Lng: 54.30254, -0.40975
OS grid ref: TA035908