OK, I give up. I've been endlessly reading up on how to tell the difference between a Cormorant and a Shag and I swear this bird demonstrates features attributed to both. To me the head shape says Cormorant so I'm going with that, but it's lacking the colouration on the face that would really confirm it. As seen on Farne, where both are definitely resident.
They’re the same bird, according to the rhyme: “The cormorant or common shag Lays its eggs in a paper bag…” So now you know!
They’re not the same bird at all, there’s 35 cormorant and shag species in the Phalacrocorax genus. The pic above is a cormorant- you can tell by the head shape. Shags are generally smaller and slimmer but always have a steeper forehead than cormorants.
Mal – thanks for the info, which seems to corroborate my guess and for the same reasons. Phew.