...since there was so much interest in the hatch, I thought I'd post some images of the new dungeon level at the BigRedBatCave. Above is the larger end of the space, with the old, damp, clinker floor removed. This will, shortly, be covered with a concrete slab.
Here's the area under the hallway, before painting.
...and after, now coated with a damp-resistant slurry, in a dungeon-friendly battleship grey. I may add some manacles.
Next step is for the concrete slab to go in. In the coming weeks, I plan to get the pipework tucked away and put in some ventilation.