“It looked way too small at first,” said Rachel, staring at a hole she was about to drop through. Twice.

Getting to Mouldridge Mine on Tuesday evening was itself an adventure. Katie and Rachel were on the train from Manchester when it ground to a halt near Chinley. A fault. Then the announcement: the train was turning back. Judith, already driving out of Buxton toward the mine, saw the messages and swung her car around. “Turning round now!” followed by a smiley face. Twenty minutes later she was at Chinley station, collecting two slightly bewildered cavers from the platform. The train couldn’t get them to Derbyshire. Judith could.

Emma, who’d originally offered to pick them up from Edale, met everyone at the farm instead. The evening was back on.

Mouldridge is a compact old lead mine near Matlock, and compact is the word. Tunnels branch and reconnect. Passages loop back on themselves. The place is a friendly little maze, and Emma discovered this the hard way. “Next time I think I’ll bring a big bag of marshmallows so I can mark where I’ve been in all those tunnels,” she said afterwards. “Evidently my sense of direction has got up and left me.”

The banana slide was a highlight for most of the group. It’s a smooth, angled chute you can slide down, and both Emma and Rachel picked it as their favourite bit. Emma hadn’t done it before. Rachel loved it. Dan, meanwhile, was fixated on the hole.

Not a metaphorical hole. An actual hole in the floor that you lower yourself through into the passage below. “Loved dropping through the hole a couple of times, which was my favourite bit,” Dan said. Rachel agreed, though she’d needed a moment to convince herself it was possible. The hole does look too small. It isn’t, but it looks it, and the gap between those two facts is where the interesting part of your brain kicks in.

Dan also spotted the beginnings of stalactites forming on the ceiling, tiny and young and barely there. “Pretty special,” was his verdict. People have dug through this mine for centuries, and the rock is still doing its thing. Quietly building something new in the spaces people carved out.

Everyone mentioned the teamwork afterwards. Rachel, who’d already had to survive a train breakdown and an emergency car rescue just to get there, said it best: “Everyone always gives great support, which makes things less scary.”

Then they climbed out into the evening air, and the heat hit them. After the cool of the mine, the May warmth felt tropical. Dan mentioned it. Everyone felt it. That particular slap of summer after hours underground, where your body has completely forgotten what season it is.

Rachel thanked Emma and Judith for sorting out “all the train palaver,” which might be the most British understatement of the evening. A broken train, a U-turn on the A6, a pickup from a station that wasn’t on the original plan, and nobody missed a thing.

Judith led the trip. The mine didn’t care about the chaos above ground. Below it, everything clicked.