Thanks Mike, most interesting. That settles the "90m long chamber" then. So Phil Hendy went down! He was in my house a couple of days ago, but he's not on UKcaving. I'll ask him, see what he remembers.
If the farmer stopped chucking carcasses down it may be more salubrious by now but from what axbridgecaver said the farmer is resolute that he won't give access.