It’s a Saturday afternoon in mid-February, and halfway up Wales’s highest mountain the weather has taken an apocalyptic turn. A gusting wind flings billowing sheets of rain across the craggy terrain and stirs the water of the glacial valley lake below like a giant ladle. Hikers loom out of the deluge, hoods pulled into tight circles around expressionless faces. It seems a curious time to be out on Snowdon, or Yr Wyddfa. In their defence, it wasn’t like this earlier in the day. It wasn’t like this 20 minutes ago.

There’s a crackle on the Land Rover’s radio and the phones of the three members of the Llanberis Mountain Rescue Team’s Mobile 2 unit ping in unison: 3pm on a Saturday is dubbed “work o’clock” by these volunteers — fatigue and fading light working in menacing tandem. I check my watch: it’s 3.09pm. The casualty is a woman with a suspected broken leg on the Pyg Track, one of the toughest of six main routes leading up to Snowdon’s 1,085m (3,560ft) summit. She’s immobile. Wet. Cold and getting colder. Mobile 2, which has been patrolling the Miners’ Track — the old copper mine trail that runs broadly parallel with the Pyg — is closest. A swift U-turn is performed and the Land Rover powers off.

Driving is Jethro Kiernan, 53: hardy, unflappable, a lick of grey running through his hair and coppery beard. A semi-professional photographer, he’s been volunteering with mountain rescue for four years. Riding shotgun is Jess Ward. Tall and athletic, with a calm authority that belies her 23 years, her day job is training firefighters and paramedics in specialist rescues. Jonathan Boothby completes the trio. The affable 33-year-old videographer is near the end of his 12-month stint as a “provisional”, a rookie recruit. Like a new signing for a football club competing on multiple fronts, he’s been getting a lot of game time. 

That’s because, of the 47 mountain rescue teams in England and Wales, Llanberis is by far the busiest. Its area of operation is small — just over 100 square miles, less than a third the size of patches such as Rossendale and Pendle in east Lancashire — but at its heart lies the honeypot peak of Snowdon, the most visited and climbed mountain in the UK. Nearly four million people converge on Snowdonia National Park, or Eryri, a year, with about 600,000 intent on reaching the park’s totemic peak.

Last year the team had 308 callouts — 30 per cent higher than any previous year, putting unprecedented strain on the volunteers and the antiquated funding model that requires teams to raise most of their operating budget themselves. “I’ve only ever known busy,” says Ward, who joined the Llanberis team two years ago.

The Land Rover pulls into Pen y Pass car park, launchpad for the mountain’s eastern trails. The trio grab head torches and first aid packs and, against the flow of rainwater and dispirited hikers, set off up the Pyg’s steep rocky track on foot.

“We tend to see people at their absolute lowest point,” Kiernan had explained earlier in the day, during a rope-rescue training session on the other side of the valley. “It’s like the antithesis of Instagram.” 

This unfortunate woman, when they reach her, is certainly that. She’s propped against a boulder, groaning under an ineffectual pile of sodden coats and towels. Diminutive of frame, she’s cradled by another female hiker, a Samaritan passer-by whose teeth are chattering audibly. The casualty’s husband, shivering and overwhelmed, looks on. Their day really wasn’t supposed to turn out like this.