My dad recently found this bone that we believe to be a skull on the beach at Frinton on Sea in Essex. It was washed up after some of the recent stormy weather. It is pretty worn as you can see, and most of the cavities are filled with what appears to be very hard old clay.
It is approximately 150mm long, and 140mm wide at is widest part.
Sorry to disappoint you after such an exciting suggestion of a whale skull BUT this is the cranium of a Cow. The articulations for the first vertebra are typical for a herbivore and most unlike any cetacae (whale/dolphin/porpoise). The shape of the top of the skull is saddle shaped in a cow and fits best with the photos.
Photo 3 - side of the skull, neck on the left nose (missing) on the right
Photo 4 - back of the skull where it attaches to the neck
Photo 5 - undersurface
Photo 6 - front view, this shows the back wall of the nasal cavity, towards the table, and the saddle shaped top of the crainium