langcliffe said:A more realistic project would possibly be to attempt to enter the cave from the sink area, some half a kilometre or so from the end of the explored cave. The YRC pushed a bedding plane passage at the sink for some distance, and also entered a level which was supposed to have crossed the line of the cave. The former got too tight, and the latter was seen to have been driven through some pretty poor ground, and they encountered a major rockfall.
I had a trip down one of the sinks many years ago when I lived up north and I can confirm that it did indeed get far too tight. There were a number of encouraging signs, however, and it would be well worth another look to reassess whether further progress could be possible by employing modern digging techniques. Just the place for a self-confessed thin-man like Alex!