I saw an article in an archaeological group about a standing stone with tafoni. The state be was limestone iirc. Not having heard of the term before I looked it up. It struck me that the appearance was quite similar to the crease limestone that you get in the Forest of Dean. But it seems unlikely to be the same due to the amount of crease limestone? Anyone care to enlighten me?
https://en.m.wikipedia.org/wiki/Tafoni

Also loosely termed boxwork or laticing, but these are found in finely veined rock that has etched out. Visually similar but different mechanisms? The tafoni can be marine or fresh water from what I have seen. It seems to be related to the breakdown of a surface skin of hard, weathered rock, allowing a core to erode out. Curious and picturesque

Is that this stuff? Photographed under a ledge of bedrock (lying on my back with a wide-angle lens) somewhere near Calver.

That's the lattice / boxwork type, with small resistant veins around more soluble host material. Typical of mineralised rocks or ones that have been subjected to a lot of stress. True tafoni is more well rounded on or in the surface of a weathered surface

yes, from recollection of looking at the same bit of rock (in fact, I think it was there at the time the photo was taken) the proud bits are calcite/fluorite stringers that have resisted the erosion of the host rock.