Britain's child slaves: They started at 4am, lived off acorns and had nails put through their ears for shoddy work.
The tunnel was narrow, and a mere 16in high in places. The workers could barely kneel in it, let alone stand. Thick,choking coal dust filled their lungs as they crawled through the darkness, their knees scraping on the rough surface and their muscles contracting with pain.
A single 'hurrier' pulled the heavy cart of coal, weighing as much as 500lb, attached by a chain to a belt worn around the waist, while one or more 'thrusters' pushed from behind. Acrid water dripped from the tunnel ceiling, soaking their ragged clothes.
Many would die from lung cancer and other diseases before they reached 25. For, shockingly, these human beasts of burden were children, some only five years old.
Robert North, who worked in a coal mine in Yorkshire, told an inspector: 'I went into the pit at seven years of age. When I drew by the girdle and chain, my skin was broken and the blood ran down … If we said anything, they would beat us.'
Impoverished: Children who worked were subject to appalling conditions. Many who worked died before they reached 25
Another young hurrier, Patience Kershaw, had a bald patch on her head from years of pushing carts - often with her scalp pressed against them - for 11 miles a day underground. 'Sometimes they [the miners] beat me if I am not quick enough,' she said.
The inspector described her as a 'filthy, ragged, and deplorable-looking object'.
Others, like Sarah Gooder, aged eight, were used as 'trappers'. Crouching in the darkness of the tunnel wall, they waited to open trap doors which allowed the carts to travel through.
'I have to trap without a light and I'm scared,' she told the inspector. 'I go at four and sometimes half-past three in the morning, and come out at five-and-half-past … Sometimes I sing when I've light, but not in the dark. I don't like being in the pit.'