Confidence: It's likely to be this, but I can't be certain.
Notes: 3 barbels rules out the Five-bearded rockling. Three-Bearded and Shore Rockling are slightly more difficult to seperate as both have 3 barbels in the same positions. I think this fish is neither reddish coloured enough nor spotted/blotched enough to be the Three Bearded Rockling. The Marine Life Info. Network states-"The three-bearded rockling, Gaidropsarus vulgaris also has three barbels around its mouth but can be distinuguished from Gaidropsarus mediterraneus because of its very different colouration, which is reddish brown with obvious blotches." It also states-"The corners of the mouth barely extend past the eyes." I think that is shown in the 3rd picture. Final pic shows one of 2 very tiny fish lice attached to the fish. The fish was 24cm long.