Phylum: Rhodophyta   Family: Bangiaceae

Porphyra linearis Greville, 1830

Winter Laver

Zone-forming on rock in the upper intertidal and splash zone of semi-exposed and exposed shores, generally distributed; a winter and spring annual appearing on semi-exposed and exposed shores in November and persisting until February or March. - AlgaeBase website

References: 
Brodie & Irvine (2003)- Seaweeds of the British Isles, Volume 1 Rhodophyta, Part 3B Bangiophycidae