Dr Stroud diagnosed in himself hypoglycaemia, a blood-sugar disorder which has been known to bring on coma, and death in as little as 24 hours, according to Laurence Howell, who handled the expedition's radio communications in the UK.
'There was no way they could go on,' he said. 'In the old days, they'd have died.'
Sir Ranulph, 50 in March, and Dr Stroud, 37, had originally intended to walk to the sea at McMurdo Sound, but were airlifted off the Ross ice shelf during Thursday night. They are now resting at a temporary camp at Patriot Hills in western Antarctica. Both men are emaciated and Sir Ranulph has severe infection and frostbite in one of his feet.
The nightmare was that after their tumbling descent of the Beardmore Glacier, where they sometimes covered 25 miles or more a day, the two men would rapidly deteriorate during the slow slog over the flat ice shelf.
They reached the base of the glacier on 7 February, and by their own computation and that of other polar experts had succeeded in their main goal of crossing continental Antarctica. But they pressed on over the ice-shelf, apparently to log mileage for contributions to the Multiple Sclerosis Society.
For the other expedition members, the fear was that both men might descend into a spiral of decline which would rob them of their judgement. They decided to stop on Thursday.
The men hope to be back in Britain as early as the second half of this week and will go straight to the Army Personnel Research Establishment at Farnborough, where Dr Stroud has set up tests for his metabolic research. However, delays at Patriot Hills so late in the Antarctic summer tend to be measured in weeks.
The latitude with attitude, Review