Cormorant or shag?

I'm no bird expert and I'm more used to having a heron watch over my attempts at fishing, but today this appeared in a tree.

I've always associated cormorants with the coast and the sea (which is not far away as the cormorant flies!) so I'm not used to seeing one inland.

I think a shag has a slimmer neck so I'm plumping for this being a cormorant.

Whatever it is it scared the fish away today! Or it may have been to do with the stillness of the water as the extra photo shows( nothing to do with my casting skills of course).