Even accomplished climbers who have tackled the world's most challenging mountains under-estimate "the hill", says Dr Brian Tregaskis.

For 25 years he has been providing medical assistance to stranded, lost and injured walkers on Ben Nevis, as part of the Lochaber Mountain Rescue (LMT) team.

Many are unprepared for the rapidly changing weather or the challenges that await on the UK's highest peak that is known as the 'venomous' mountain in Gaelic.

Tales of plimsole wearing tourists aren't fiction. However, even the least equipped winter walker won't receive any moral judgement from the men and women who leave their jobs and beds to go out in all weathers to find them.

"Mountain Rescue is run by Police Scotland. If there is anyone to be given a talking to, we leave it to the police," says Dr Tregaskis, who is more usually found treating patients at Belford Hospital in Fort William, which is Scotland's busiest rural general.

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"Our job is go out and rescue people in need.We are all climbers or hill-goers ourselves and realise it could be one of us so we don't criticise. The hills are there for everyone to enjoy."

Last year, marked the 50th anniversary of the founding of LMT but the pandemic put paid to the volunteers' very own rescue party.

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Dr Tregaskis says it's likely there was some sort of volunteer rescue effort for many years before that by individual climbers and the police.

He signed up as a volunteer, shortly after he started working at Belford hospital, aware that there was a need for better medical provision for injured hillwalkers.

READ MORE: Walkers rescued after 'short-cut' leaves them stranded on Ben Nevis gully 

"Although everyone was brilliant at rescue, we felt we could get improvements in the way we managed casualties. The knowledge of how to manage injuries was perhaps not so big back in the day.

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"Of course, it's light years on from that now. There's a lot more education for our team members on how to manage casualties and how to get them off hills and the care is as good as you would get in any accident and emergency department."

There are roughly 100-120 call-outs a year and Dr Tregaskis says he is able to assist on around 80%.

READ MORE: A week in radio: The highs and lows of Ben Nevis

"It needs to be a very illuminated employer that will allow people to go away while they are on call," says the father-of-four who is originally from Cornwall and lives in Spean Bridge, nine miles north of Fort William.

"It helped the patients, as they tended to come in here anyway so as long as the hospital is covered, they have always been fairly reasonable about going on rescues in work time.

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"One of our problems today is that employers in Fort William were always very good at letting their employees get away but increasingly that's more difficult for them, which means we are often struggling mid-week.

"Part of our charitable function was to make up people's wages when they went away from work but now employers are not prepared to let some folk get away. 

"We've made a big recruitment drive over the past few years and got a lot of youngsters, which brought the average age of the team down a fair bit. But we get enough people usually."

More than 150,000 people ascend Ben Nevis each year and there are several deaths annually, caused by a number of factors.

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There are multiple routes up the 1,345m (4,413ft) mountain, ranging in difficulty from easy to extremely challenging.

The hardest routes are said to be the Observatory Ridge and North East Buttress routes, which are both graded Very Difficult rock climbs in the UK grading system and require rock-climbing and safety equipment. Previous scrambling and hillwalking experience is recommended.

READ MORE: Why has Google Maps' Ben Nevis route been called dangerous?

Lochaber Guides says that good weather is a must, even for those taking the relentless zig zag mountain path. It is a popular tourist destination but its weather has been described as the most ferocious to be found anywhere in the UK.

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The number of call-outs has increased in recent weeks, says Dr Tregaskis, with many un-prepared for the snow that remains at the top of Ben Nevis for most of the year.

"I'd expect that to continue for the next few weeks. Then it will be the real winter hill-goers who only really call if they get into a pickle."

A keen hillwalker himself, he enjoys long walks in the winter, including treks up the Ben.

"I like being remote. But once you got off the main road in the Highlands you are a potential rescue. You only have to walk 100 yards to be hard to find," he says.

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"Rescues fall into different categories. You have the absolutely tragic, so the people killed in avalanches and we do our very best for them - to the extremely funny like the guy who lost his boots on the mountains and we had to bring him up a pair.

"My favourite rescue of all time was the walkers who decided to go down the mountain on their backsides because they had watched mountaineers doing it.

"You use your ice axe to stop you but of course they didn't have any ice axes and smashed into some rocks.

"A third member of the party came down after them and said he had followed the dog zig-zagging his way down. The dog had more sense."

He says he doesn't really get nervous even on the trickier rescues. "We are wary, we give respect to the hill. It's notorious that even the world's most accomplished climbers come to grief on Scottish mountains, even if they have climbed the Himalayas and the rest of it.

"The weather is the main factor in most rescues, poor navigation is second. If you are lying still on a mountain you rapidly become dehydrated and hypothermic. Don't under-estimate Ben Nevis."

As a registered charity, LMT relies heavily on donations but receives a very welcome, annual block grant of around £20-£30,000 from the Scottish Government.

It hasn't increased in the last 14 or 15 years but many teams in the UK get no help at all, he says.

It costs more than £100,000 each year to run the team - a single rope to lower someone from the top of Ben Nevis can cost £1000 and may only be used once. 

"Increasingly we use drones, we put them out in very challenging conditions and we lose them and it's £1000 a time for a drone.

"We use them to search avalanche areas and we use them to try to locate people so we don't have people in hazardous areas. We've got a couple of drone drivers who are well qualified and have their commercial pilots licence. That all costs money."

Now 63, Dr Tregaskis says he'll continue assisting on rescues until he is "incapable" and after that he intends to pitch in, albeit in a back-seat role.

"The great thing about mountain rescue is, we are a close knit community. We rely on other people for our safety and that reliance breeds great friendships."