ID this bird for me, please

Q While on holiday in Pembrokeshire I saw this bird but could not identify it by books in my library. Can you help me identify it, please? Kelvin Gardiner A This black-and-white bird swimming on what we presume is the sea, is a Guillemot. The compact shape, and longish, dagger-like bill are big clues, as is the strikingly black-and-white plumage and the very long primaries in the wings (the long, pointed flight feathers). The similar Razorbill has a laterally flattened bill (a bit like an old fashioned cut-throat razor). The very rare Brünnich’s Guillemot as a slightly thicker bill and a lacks that thin black line behind the eye, (having a more extensive dark crown). Note that this bird is in winter plumage: in summer its head, throat and breast would be dark, blackish brown. referred to as the Hedge Sparrow, although it’s actually a member of the accentor family. Its preferred habitat is exactly the sort of area that you mention, as well as parks and gardens, but it can easily go unnoticed because of its preference for foraging on the ground close to cover. In terms of ID, the relative thinness of the bill sets it apart from sparrows and finches, while the bill is longer than you’d find on tits. Its plumage is a mixture of brown (hence the ‘dun’ in Dunnock), and grey, and while it might not immediately catch the eye, when seen well (as here), it’s really rather beautiful.