Can't find 'Rope boy' - just 'Rope mam' = A man employed to maintain and extend, splice or install haulage ropes.
Other than HPW - Geoff Glass & Alan Dickson (Barnton Facebook group) two of the web sites I have used for pit terms are :-
https://www.healeyhero.co.uk/rescue/glossary/glossary.htm
&
http://www.dmm.org.uk/books/terms_a.htm
Nothing about Rope man or boy in the dmm list.
NB. the healeyhero site http://www.healeyhero.co.uk/rescue/glossary/glossary.htm t says :- his site is Glossary of words that are generally specific to the mining industry: Some have a two or three fold meaning, some have gone out of use, some are local to Derbyshire, Leicestershire, South Yorkshire and to Nottinghamshire, and others are general to the British Coalfields.
As there wasn't a reference to Rope boy I looked at Haulage (from the Rope man definition) and it has this :-
Haulage Boy, (1) aged 13 to 18 usually employed lashing or clipping and un-clipping tubs on an engine driven (moving) haulage rope on main roads or pit bottom area.
Haulage boy (2) could also be one say 15 years plus employed getting tubs or jotties of supplies to a face and empties back in panel gates by engine driven haulage rope, or ganging same by a pony. The age of starting work was 13 from 1880s up to 1913, then 14 from 1930s to 1948, 15 up to 1960s, thereafter 16 plus.
Haulage boy (3) generally a young boy 13 to 15 assisting an experienced person doing the above jobs (description sometimes varied pit by pit).