That was Trevor Ford's follow-up article to his original Longcliffe article in the PDMHS Bulletin, where he speculated that the miners must have used a chain in the main shaft owing to the size of the rope-grooves. He rigged up a test block of limestone in the lab at Leicester Uni, and I think he may have just used string, with some weights and a pulley, and cut into it in about an hour, and so revised his opinion!
Our hauling ropes were starting to leave a groove on the overhangs after only a few weeks, and so we covered them up with conveyor belt. But now there are three grooves - one about 8cm, one inside at about 4cm, and ours at 1cm in the middle. This shot is just after we got started, so pretty much untouched miners' grooves in solid calcite - which here, incidentally is one of the toughest substances I've ever encountered in caving.