Mary Lamb, 65, suffered a chest infection, stomach bug and was ‘10 minutes away from hypothermia’ during the gruelling three-day challenge. But she battled through it to reach the summit of all three mountains – Ben Nevis, Scafell Pike and Snowdon – with the help of the British Army and her assistance dog Sheldon.

“Honest to God, I don’t know how I got through it,” said Mary. “I was told it couldn’t be done and so I was just going to do it and that was all there was to it. You…