Jeremy Laurance: A remarkable feat for a man half his age

To climb Everest is a feat at any age. To climb it successfully at the age of 65 is worthy of special celebration.

What makes reaching the summit among the toughest physical challenges around is the thinness of the air. Above Base Camp the air is so lacking in oxygen that climbers are forced to breathe much harder than they would at sea level and to make repeated stops to rest. That is punishing for anyone, but especially so for someone not in the first flush of youth.

The weather is so unpredictable there may be only a narrow window when it is safe to climb, and speed is essential.

The body needs time to acclimatise to the low oxygen conditions so climbers must ascend and descend repeatedly, going a little further each time.

Sir Ranulph Fiennes had one major advantage over the younger climbers who make the attempt – experience. Having tried twice before, he knew where the barriers lay.

Lack of oxygen is the biggest hazard. It can lead to dizziness and confusion, the cause of countless deaths on the mountain. Like every Everest conqueror who survives, Sir Ranulph will be blessing his luck.