sir ranulph , 71 , completed the most gruelling stage of the desert race today , but was taken straight to the medical tent .
he was forced to lie down intermittently during the last few hours of the run because of fears he would not be able to finish the stage and described the experience as ` more hellish than hell ' .
he previously suffered two heart attacks and underwent a double heart bypass , a cancer operation , and is in an ongoing fight with diabetes that