On a mild spring morning in 2017, Clare Sutton, a 31-year-old biology teacher, a single mother and one of my closest friends, was running a 10-kilometre race in the village of Poynton, close to Manchester, when she collapsed 100 metres or so short of the finish line. One of her friends, a nurse called Helen Thompson, had just finished the race. Assuming that Clare had fainted, she grabbed a bottle of water and a banana and rushed to help. As soon as Clare came into view, Thompson realised things were much, much worse.
“Clare was completely lifeless,” Thompson told me.
