Much of Blackgang Chine has fallen off, yes, although they've adapted pretty well, just repeatedly moving everything further inland, and adding a section called "The Disappearing Village," in which you can read all about the landslides. It is quite sobering to see how fast the coast changes. You can do a walk one year, and look down and see last year's footpath lying shattered halfway down the cliff.

And, yes, it does look very like a rocket. The lighthouse story is doubtless just a cover story, to keep us from learning the truth about the alien-inspired medieval space programme. :-)