Fresh from finishing the Marathon des Sables, Ranulph Fiennes has become the oldest Briton to complete this ultimate endurance test.The world's greatest living explorer, has travelled to some of the most remote, dangerous parts of the globe.Well-known for his experiences at the poles and climbing Everest, he has also endured some of the hottest conditions on the planet, where temperatures regularly exceed 40 degrees and, without water and shelter, death is inevitable.