There are several interesting shafts in the area. This shaft was under a fissure with a few boulders in the roof. Rocks dropped in create an impressive BOOM.
The entrance is in the bottom of the rift. You scramble down into the rift and go under a few blocks above you to find the 1 meter diameter entrance. Throwing rocks into the entrance creates a boom, suggesting larger spaces below.
The rock at the top was a bit funky due to frost etc.
The entrance was rigged with a pulse in a block on the floor and a Y hang from 2 pulses on either side of the opening. The shaft turns out to be about 15 meters deep and about 2 meters in diameter.
The floor is rocky with no way on, unless you are a Mendip caver. No need to return until every other lead on the plateau is complete.