When I used the Field Key to British Red Seaweeds, https://fsj.field-studies-council.org/media/778992/aidgap_red_seaweeds.pdf, this red seaweed key out to Phyllophora pseudoceranoides, and the resemblance to diagram on page 79 looked a good fit. The long long stipe, divides into branches, and expands into a fan shaped blade, relatively thin, purplish red in colour. Checking gbif it has been recorded in Loch Ewe, and looking through the gallery, there are a number of which show good agreement. However, it must be said that is a great deal of variation.
.
I also think the description and images in https://www.algaebase.org/search/species/detail/?species_id=124 are a good fit.

Main navigation

• Observations
• Projects
• Species browser
• Species dictionary
• News stories
• Articles