The International World Extreme Medicine Conference in London is not for the faint-hearted.

As I sneak into the back of the main lecture hall, record-breaking polar explorer Sir Ranulph Fiennes is in full flow – vividly describing the state of his companion’s frostbitten foot during an Arctic expedition. Fiennes details how a plate of rotten skin peeled away in his friend’s boot exposing the nerve ends. There are pictures. Even some of the hardened medics in the audience have to look away.

Sir Ranulph has travelled to the ends of the Earth to tackle the coldest, highest and most dangerous environments. Several times he has barely lived to tell the tale – suffering starvation, sickness and the loss of fingers to frostbite, some of which he amputated himself.