Last week the swimming season at the beach’s ocean baths began … and the sea water was  absolutely freezing, like melt-water from the alps. 16 degrees said the sign, but it felt like maybe 12 degrees. All the same, we plunged in, gasping and yelping. After about four laps, the tingling feeling goes, the extremities either retreat or become numb. About 15 minutes later we emerged, a deep shade of purple.

Yet every day, throughout winter, some old fogeys take their constitutional dip: half an hour or more, marching up and down, waist deep, or swimming their laps. How do they manage? I would suggest that at a certain age the nervous system simply packs it in, sensations disappear, and you can plunge into Antarctic waters as though in the tropics. The brain too slows down, since any normal person will find that basic functions are fatally affected if you swim in less than 16 degrees.