The tensest part of the Beales’ race to climb the three highest mountains in Scotland, England and Wales in 24 hours came not as they were skirting the sheer 2,000ft (600m) drops on Ben Nevis, nor as fatigue, sickness and sleep deprivation sapped their will to beat their deadline, but as the family of six sat motionless in a minibus on a North Wales motorway.

“We’d had a good run till then,” recalls Tony Beales. “Ben Nevis was straightforward. And Scafell Pike was empty, and beautifully sunny, so we made good time there. But as we headed for Snowdon, the sun had brought out the crowds and we sat in traffic with precious minutes ticking away. It was horribly frustrating.”

Veterans of active family holidays and hearty weekend hikes, the Beales — Tony, 52; wife Kathie, 55; sons Steve, 24, Joe, 22, Dave, 18, and Mike, 14; plus dogs Hampton and Lucy — all signed up for the Three Peaks 24-hour Challenge one December evening in 2002 when Tony, a software company director, casually dropped it into conversation. Past climbing glories included an unsuccessful but thrilling shot at Cotopaxi in Ecuador in 2002 and, for Tony, scaling Kilimanjaro the year before.

Even though the Beales were pretty limber, Kathie prepared for the challenge with a daily half-hour hike up 13,000ft Holcombe Hill near their home in Bury, Lancashire, come rain, shine or pitch darkness. “Walking keeps me sane,” says Kathie, who teaches English and theatre studies at Bury Grammar School. “It’s the ideal start to a stressful day in the classroom.”

Weekend outings walking mountains expanded in the months before the appointed date — last June 28 — and dry runs up Snowdon and a snowy Scafell Pike, and a half-term break clambering all over Cumbria raised the bar. A “commonsense diet – cutting down on the obvious” — left both Tony and Kathie with half a stone less to carry (achievements rather eclipsed, however, by Hampton’s victory in the local vet’s Slimmer of the Year competition).

When the big day came, drizzle at the foot of Ben Nevis wasn’t the only bad news as the Beales piled out of the minibus at 6pm to start their first ascent, 4,090ft. “Our exhaust had arrived in two pieces, so we set off, leaving Robert, our driver, on the phone to the RAC, not knowing if the day was over before it had begun,” Tony says.

Setting a decidedly unleisurely pace, they soon broke through the clouds and were rewarded with golden evening light all the way to the top. “It was like something from the Bible,” Kathie says, “all these great beams of sunlight streaming through.” Ben Nevis’s peak was reached in plenty of time to get down before the sun, so Dave was permitted five minutes on his mobile for a blow-by-blow account of who was dancing with whom at the school leavers’ ball he was missing that night.

The Beales tucked into a high-energy feast of chicken, pasta, rice and bananas in the revived minibus, then did their best to sleep as their driver, a friend Tony had recruited from work, kept up the buffeting pace to beat the 24-hour deadline to Scafell Pike in the Lake District. A flawless summer dawn did little to cheer Joe, sleepless and carsick, as they tackled the steepest of the three climbs, rising 3,000ft in 2½ miles.

“What surprised me was how many others were doing the challenge, and it was nice to keep seeing the same faces and the encouragement we all gave each other,” Joe says.

A few minutes were all the family allowed themselves to drink in views “so clear and sunny, we could see the colours of front doors on the Isle of Man” before heading for Snowdon.

Finally escaping Welsh gridlock hell, they arrived at the mountain at 1.50pm, to further frustration. Crowds of daytrippers made a steady pace impossible, and knees and thighs felt every one of Snowdon’s 3,560ft. “But when we reached the top, we knew we’d done it, we were well on time,” Tony says. “We even let the dogs, who I think would have run up another mountain afterwards, have a swim in a lake on the way down.” Driving home, the only celebration on everyone’s mind was a long soak and a good night’s sleep.

Ten months on, the Beales are catching their breath after a spectacular round two. This time Steve’s girlfriend Alex joined Team Beales for a camping trek through the Nepalese Himalaya to the base camp on Mount Everest, highest peak of them all.

Times recommends

• Think yourself slim with our hypnodiet podcast
• So, what really makes you happy?
• Paparazzi: A flash in the pan