An experienced mountain climber died in the Himalayas after his guide failed to address symptoms of altitude sickness.

Andrew Dean, from Wimbledon, embarked on an adventurous 11 day trek through the Pir Panjal region in northern India in October 2012 with Cumbria-based KE Adventure Travel, supported by Indian based KVT who provided a guide.

At an inquest into his death at Westminster Coroners Court on Friday, December 6, the 57-year-old retired civil servant was described as a fit and healthy man with previous experience of trekking having conquered Everest base camp in 2010.

Throughout the first three days of the trek Mr Dean was seen as one of the "fittest" of the group often at the front.

However on the fourth day there was a marked change in his fitness as he struggled to keep up complaining he was tired having had a restless nights sleep.

The guide, named in court as 'Bally' Singh, hung back with Mr Dean while the rest of the group went ahead and eventually offered Mr Dean Diamox - a drug commonly used to treat altitude sickness.

When he refused Mr Singh instead offered Mr Dean the opportunity to be carried up the final ascent that day on a pony, which he accepted.

It was on the descent that Mr Dean began to deteriorate with Russell Cargill, another member of the group, describing in court his own sense of unease about his health and now "yellow" complexion.

Soon after Mr Dean arrived at the camp and that evening he collapsed and died.

A post mortem found the cause of death to be a cardio respiratory arrest and pulmonary oedema caused by altitude sickness.

Guide Mr Singh had more than 15 years experience of trekking within the region and was properly certified in first aid and altitude sickness.

However in court professor Micheal Mythen, an expert in mountain sickness, said disturbed sleep was a very well recognised symptom of mild acute mountain sickness and that, coupled with an intolerance to exercise, it should have been clear Mr Dean was suffering with the illness.

He said: "Nothing is absolute but there is a golden rule that anything that’s not quite right is mountain sickness until proven otherwise.

"A general rule is not to use ponies if you think they might be showing sickness of acute mountain sickness.

He added: "To offer Diamox, which would suggest that the individual thinks this might be mountain sickness, and to ascend from there is not logical."

Recording a narrative verdict Coroner Shirley Radcliffe said: "Diamox is used to treat altitude sickness and you wouldn’t expect someone to offer it unless they had a feeling that there might be something related to altitude sickness.

"Mr Dean refused.

"I think at that point it would seem, on the basis of Professor Mythen, that there should have been a clear period or opportunity to do a holistic assessment of the situation.

"Here is a man with previous trekking experience who was fit and healthy who’s had a night of disturbed sleep and unable to keep up with the group who has been offered Diamox.

"It really is the responsibility of the guide at the point that anything that is odd is deemed to be altitude sickness until proven otherwise. "It didn’t seem as if there was any thought to proving otherwise."

She added: "Unfortunately Mr Dean was offered to ascend the final part of the ascent on a pony which in the opinion of Professor Mythen is the wrong thing to do because it allows the person somewhat temporary relief and can delay the onset of the worst of the symptoms.

"What should have happened was a descent at the time his symptoms were demonstrating themselves and he was quite clearly suffering from altitude sickness.

"Had that re-assessment and opportunity to have taken a descent take place at that time professor Mythen believes it’s more likely than not he would have been alive today."

Mr Glen Rowley, director of KE Adventure travel, said in court that in 30 years of organising treks throughout the world he had never experienced a death from altitude sickness.

He said that KVT, a company with more than 25 years experience in running treks, had come highly recommended and that he had had no concerns about the standard of their guides.

Following the incident the company adjusted the aclimitisation stages of the trek and made it a requirement for all guides to carry oxygen or PACS (portable altitude chambers) on all treks.