George Mallory : biography
Although some recent climbers have climbed Everest without the aid of supplemental oxygen, these are extraordinary athletes, fully hydrated and wearing the latest wind-proof clothing, or Sherpas who are genetically endowed with high-altitude capability. Like the four-minute mile, this was not within the capabilities of climbers of the period. Thus, the best chance for Mallory to have reached the summit would have been if he had relieved Irvine of his oxygen at the First Step and sent him down to safety. However, the rope-jerk injuries around Mallory’s waist tell the story that the two were roped together when they fell. Other historians suggest that, after having seen the extreme technical difficulty of the Second Step, the two may have switched to the "Norton" Route, via the Great Couloir. While theoretically possible, there is no physical evidence for this supposition.
Another possibility, prompted by Mallory’s remark in his last note to John Noel that they would "probably go on two cylinders", is that the pair carried three, and not two cylinders each (Mallory’s "probably" implying that the choice was between two or three, as a single cylinder would clearly be inadequate). Mallory’s oxygen rig was not found with his body, and neither climber’s backpack-style oxygen rig has ever been found.
Some believe George Mallory chose his climbing partner (Andrew "Sandy" Irvine) because he was excellent at repairing the oxygen tanks that had been controversial during that time.http://www.pbs.org/wgbh/nova/everest/lost/mystery/index.html, http://www.pbs.org/wgbh/nova/everest/lost/mystery/mallory.html
The difficult "Second Step"
Experienced modern climbers have mixed views on whether Mallory was capable of climbing the "Second Step" on the North Ridge, now surmounted via a aluminium ladder first permanently fixed in place by Chinese climbers in 1975 to bridge this very difficult pitch. It is alleged the Second Step was first climbed by the Chinese in 1960. However, Mallory and Irvine may have reached these heights in 1924. It was climbed "free" (without artificial aid) by Spanish climber Oscar Cadiach in 1985. He rated the crack that forms the crux 5.7-5.8 (5+ UIAA grading), certainly accepted as within Mallory’s ability. However, on Cadiach’s climb, the Second Step was filled with a hard snow ramp that made its ascent considerably easier than in the conditions faced by Mallory. Austrian Theo Fritsche repeated the free climb solo — that is, without rope protection — in 2001 under dry pre-monsoon conditions (as in 1924), and assessed the climb as a 5.6-5.7. Fritsche completed the climb without supplementary oxygen (as did Cadiach), wearing only a light down jacket, but it took him a solid hour to achieve—hardly what a 5.8 climb of a few metres would require. He believes that Mallory could have summitted in his clothing on a good day.
In June 2007, as part of the 2007 Altitude Everest expedition, Conrad Anker and Leo Houlding free-climbed the Second Step, having first removed the Chinese ladder (which was later replaced). Houlding rated the climb at 5.9, just within Mallory’s estimated capabilities. The climb was part of an expedition designed to film a recreation of the 1924 climb as closely as possible. Eight years earlier Anker had climbed the Second Step as part of the Mallory and Irvine Research Expedition but had used one point of aid by stepping on a rung of the ladder which blocked the only available foothold. At that time he had rated the climb at 5.10, certainly well beyond Mallory’s capability; after the June 2007 climb he changed his view and said that "Mallory and Irvine could have climbed it". But by then Anker was starring in the film The Wildest Dream, which portrays the two carrying three bottles of oxygen, probably having summited. The climbing community still remains split on the subject of whether Mallory was capable of having climbed the Second Step.