Interesting picture. This sounds alot like the underwater snake creature that was caught by fishermen in the 30s on Vancouver Island. They took pictures but later that night the creature was stolen.

looks like a seal skull, even has the 5 upper 4 lower molars

would need a better image of the skull and whole body to make sure

From the above link, it does look very similar to a seal.... I don't think it can be assumed that because it was washed up on this particular shore it has anything to do with a wild large cat.

And plus, The Sun reported it, immediately makes me skeptical.