On summit day, it was Mark who had to descend early. The group left the final camp, at 15,091ft, to set out on the final slog up the mountain's cinder track at 2.30am, lighting the way with head torches. Mark, though, had a stomach bug. 'I felt very weak and dehydrated,' he says. About an hour out of camp he was forced to turn around; George wanted to continue. 'He had no doubt in his mind,' Mark says.
As George reached the top, his father endured an anxious wait. 'I was very worried. I knew that he would be OK, but I kept looking and looking. Seeing him coming down again was indescribable.
