It is arguably advice that most mountaineers are unlikely to ever need.
Sir Ranulph Feinnes, 74, has demonstrated the technique he used to saw off his own fingertips in his garden shed after they became dangerously frostbitten on an expedition to the North Pole.
The British explorer allowed a film crew into his home as part of a new series for National Geographic in which he returns to Egypt with his cousin Joseph Fiennes, the actor.
Clamping his finger into the vice of a Black & Decker workbench, Sir Ranulph demonstrated how he took a hacksaw and carefully lopped off the tips of four fingers and a thumb over the course of several days.
“You tighten it up in the obvious manner, and you do…