Speaking through an interpreter, Ang Tsering Sherpa, the only living survivor from George Mallory's doomed 1924 Everest expedition, told a national newspaper that he did not rate the pair's chances.
"They might have got close, very close, but there is no doubt in my mind that they died on the way up, not down," he said.
He told the Daily Telegraph that it was unlikely Mobberley-born Mallory and Irvine had stood on the 29,028ft peak 30 years before Sir Edmund Hillary and Tenzing Norgay.
Ang Tsering went on to tell reporter Jules Stewart that he believed the mountaineers' equipment was too primitive to get them to the top.
But he said Mallory had been the best person to lead the ascent.
"He was young, fit and the strongest climber in the team," he said.
"It would have been nice if they had reached the top. After all, that is why they were there."
On that June morning nearly 77 years ago, Ang Tsering said he could see the climbers' final route and the weather looked fine.
"We waited for a while, then suddenly a band of cloud rolled across the mountain and the climbers disappeared from view," he said.
Mallory's perfectly-preserved body - dressed in torn cotton clothes and a hobnail boot - was found in 1999 by American explorers.
He had fractured his leg in two places after a fall 2,000ft below the summit.
On Monday, author Peter Gillman said there was now a theory that Mallory died on his way down.
"He implies that he was still going for it, but there is a theory now that he may have made a responsible judgement to turn back because he had the inexperienced Irvine to look after," he said.
"He may then have slipped on rocks that were covered in fresh snow."
Each year many visitors make a pilgrimage to St Wilfrid's Church in Mobberley where a memorial window reminds visitors of the village's connections with Mallory.
On Monday, the Rev Melvyn Gray said he often met visitors from as far afield as America who wanted to know more about the local legend.
"Those who are concerned are quite proud of him as a local character and would be quite happy if he only nearly got to the top," he said.
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