right, except it wasn't their wives, it was their daughters,
from pretty well as soon as they could walk
Children were prefered because the tunnels were so low.
According to the Factories Act of 1802, children under 9 could not be put to work & thos 9 to 13 could not work more than 8 hours. But, this only applied to textile mills & was widely ignored in any case. as were later Acts. It took the rise of organized labor unions (excuse me,
labour unions, we're talking about the UK here) to bring about an end of child labor...in the West, at least.
From Wikipedia:
Maplecroft Child Labour Index 2012 survey reports 76 countries pose extreme child labour complicity risks for companies operating worldwide. The ten highest risk countries in 2012, ranked in decreasing order, were: Myanmar, North Korea, Somalia, Sudan, DR Congo, Zimbabwe, Afghanistan, Burundi, Pakistan and Ethiopia. Of the major growth economies, Maplecroft ranked Philippines 25th riskiest, India 27th, China 36th, Viet Nam 37th, Indonesia 46th, and Brazil 54th - all of them rated to involve extreme risks of child labour uncertainties, to corporations seeking to invest in developing world and import products from emerging markets.