Who is Andrew Irvine from The Crystal Horizon Everest-the First Solo Ascent and what is their importance?

Andrew Irvine is the climber who accompanied Mallory on the ill-fated assault of Everest's second step in 1924. Irvine was an expert in the use of artificial oxygen, which the two opted to use during their ascent, based on a unanimous vote of the entire party before the pair began their climb.