When Lorraine Duncan turned 40, she decided to go “Munro bagging” — climbing Scottish mountains over 3,000ft (914 metres).

One of the best for beginners is Schiehallion, a two-hour drive north of her home near Glasgow. Lorraine, her husband and their two boys enjoyed a spring day in 2017 on its slopes. From the summit they saw distant hills and lochs below. Only when the family started to descend did strange things start to happen. Lorraine felt a tingling on her skin — which she described as like touching a Van de Graaff generator at school. Suddenly her son Rian, then 12, dropped his metal walking poles. He had been electrocuted: on his hands were burns that Lorraine said looked “black like coal”.

Suddenly everybody’s hair stood on end. The selfies Lorraine uploaded to social media went viral. Soon users were warning that the family was in grave danger: that in such an electrically charged environment they were at risk of being struck by lightning. But there was no storm for at least 40 miles. At the time, they jokingly attributed these phenomena to something else.