Confidence: It's likely to be this, but I can't be certain.
Notes: 37mm clingfish found dead on the beach following very stormy weather. Despite being dead the sucker on its belly stuck readily to the hand and to the bench top, as a plunger works. The ID of L. purpurea is based on a lengthy detailed discussion on another clingfish observation on iSpot linked below, which determines all UK and Irish shore clingfish to be the suggested species. I think it possibly lacks the colouration and markings of more mature specimens simply because it is so juvenile. Either that or its something else altogether. It was quite fresh, it didn't show any signs of decay.