‘Local people didn’t think so. It was one of those disputes that was bound to happen. Red Soil was being worked by local men, but the Magpie was being mined by labour imported from Cornwall. Anyway, it’s said that the widows of the murdered men put a curse on the mine. It never made money again.’

There were two tall chimneys surviving on the site, a round one and an older square chimney. At the base of the round chimney, Cooper found a large iron grille set into the ground. He tugged at it, and found the grille was loose and could be lifted off its bolts. It was heavy, but he had no trouble raising one side and letting it fall back on to the ground, leaving the entrance to a tunnel clear. In one direction, it seemed to lead into the base of the chimney. The other way, he guessed it must enter the engine house.

On the floor of the tunnel he could see a disposable lighter, crumpled yogurt pots, and an empty John West tuna sachet. Left-overs from someone’s picnic that could be forced through the bars of the grille.

The main mine shaft was supposed to be more than seven hundred feet deep, though the bottom fifth of it was always flooded. On a bright day, they said, you could see the water if you peered through the grille. But there was no brightness today, just the grey cloud and drizzle cloaking the skeletal trees.

Cooper stood over one of the smaller shafts. Ferns peeping through the grille were dying and blackened by frost. But below them, a couple of feet into the shelter of the shaft, he glimpsed the glossy green fronds of some plant he didn’t recognize, still thriving in the gloom, even in December. Whatever it was, it looked much too healthy, considering the lack of light and the cold wind whistling overhead.

A couple of old millstones lay abandoned on the ground, one of them broken into three pieces. The walls of the engine house ran with water on the inside. Drops of water fell from the arch and the lintels of the windows. Cooper craned his head back and watched a drop falling towards him. Before it reached him, it was caught by the wind and veered off suddenly, elongating like a tear drop as it accelerated.

The water above the flooded level of the shaft was drained by the Magpie Sough, which ran into the River Wye, away to the north below Great Shacklow Wood. That was one of the longest soughs in the Peak District, more than a mile and a quarter of it, and its construction had practically ruined the mines’ shareholders.

‘My hands are completely numb now,’ said Fry. ‘Why is it so much colder here than in Edendale?’

‘We’re completely exposed,’ said Cooper. ‘Imagine what it was like working here.’

‘I don’t want to.’