I believe in Gavin Newman's wookey film, the American 'Cave diver and psychologist' got as far as Chamber 25, described it as foul, and very far from home, before leaving Gavi to film himself pushing as far as he could into the gravel, while saying things like 'I probably shouldn't go any further, the gravel's running back over my legs'.
So the American guy may have a point........
Anyway, a diving film based in the UK would probably be less appealing to the public as it would involve small squalid sumps full of zero visibility peaty water. The footage of the dive to Keld Head is impressive, but not Hoolywood blockbuster material.