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.' ...