I was out with the camera a couple of days ago and this little bird was in the midle of the loch, hence the heavily cropped photos despite a 600mm lens! It caught my attention as it was so white in the sun. There was a winter plumage red throated diver out on the water too at a similar distance and this bird was smaller than that. I've been going through my RSPB and Collins bird guides and can't quite get a match. The nearest I got was a juvenile/winter plumage Little gull but this doesn't seem likely. Can anyone please provide me with a more experienced and definitive idenitfiaction?