The day I began this book, in the first week of May, I took my inaugural 2005 dip in the Hampstead Heath Ladies’ Pond. After a sprightly thrash among the mallards I congratulated myself on tackling the 54-degree water and returned briskly home to snuggle in front of an unseasonal fire with Lynne Cox. And then I realised what an unutterable weed I am.

Swimming to Antarctica is the memoir of the most extraordinary long-distance cold-water swimmer in the world. At fourteen Cox was training in the ocean off California for four hours a day, beginning, in the winter, when frost was still forming on her coach’s windscreen. Plastic water bottles had not yet