For the record-
A reliable verbal report from the 1970s (but lost) re Dunld Mill Hole (SD 5159 6762) shows a Dye test of 8 hours(max dye ion 12 hours) to Nether Beck Farm (SD508 710 which is 500meters downstream of the rising 3 kilometres and 30 m lower than the sump in Dunald Mill Hole!
Sump last dived by Simon Cornhill a few years ago A dangerous dive as needs clearing of tree branches etc but now polluted from the farm now .
Dunald Mill Cave separate Dye test recently
This cave heads west rather than North and would also appear to have huge potential but a definite dye test shows it acmes into a low inlet just downstream of Far Chamber in Dunald Mill hole days have been spent here over the years when a dye test would have saved that
However Dunald Mill hole more to be found someday with care also flood pulse takes4-5 hours
A description of caves in Northern caves and RRCPC Journal NO 11 +elsewhere