On a non-photography note, I volunteer for the NY Marine Mammal and Sea Turtle Rescue Program. When a whale gets beached here, it generally has been dead for some time. They usually sink and then start to decompose. Decomposition gases cause them to refloat. The wind can then bring them on to the beach. The scent of a decomposing whale is unique -- sort of a mixture of decomposing cow and skunk that brings on an instant retch. We have sand beaches here. Because of the animal's mass, we bury them on the spot. That doesn't look like a choice in rocky Wales. I speculate that it had to be cut up and hauled away. For sure, that little 4x4 in one of your shots was not going to get the whale any farther up the ramp. There's a celebrated story of an attempt to dispose of a dead whale on a California beach by blowing it up with dynamite. That resulted in huge chunks of decomposing whale flesh flying through the air. One "incoming" crushed a beach visitor's Jeep.
This one looks pretty large. I'm not an expert, but it could be a finback, which is the second largest whale after the blue. It's hard to tell because it's lying upside down. I've never seen a whale "skinned" like this one. Perhaps it was from abrasions with rocky shores? Otherwise, it looks pretty clean. Do you not have sharks in Wales? Dead whale is a shark's favorite food. It's full of the fat sharks need in their diet and it doesn't fight back. If it has been in the water for any length of time where I am, there's usually chunks torn out by sharks.