Minnie stood on the grass bank, staring down into the murky brown water. Minnie first swam in Hampstead Ponds as a teenager, but the look of the water and the unnerving feeling of swimming when you couldn’t see your hands or feet had put her off. Plus, she’d been conditioned to swim fast in those days, and the ponds weren’t the best place for speed. Swimming was the one thing Minnie had been good at as a child, a sport she could do alone, with no one jeering at her. Or if they were jeering, she couldn’t hear them with her head underwater. She wasn’t sure why she’d given it up in her twenties – life and work had got in the way. Over the last few months, she had found herself drawn back to the water.

Hampstead Ponds were old reservoirs, now open to the public to swim in. They were dotted around the edge of Hampstead Heath – a beautiful, wild parkland which sprawled across nearly eight hundred acres of north London between Hampstead and Highgate. From the highest point you could see most of London, a Legoland of buildings and skyscrapers receding towards the horizon.

Minnie had always loved the heath. It was an idyllic, unspoilt oasis of nature in an otherwise tamed landscape. It served to remind the homogenised city dweller what wild grass and tumbling, tangled tree roots looked and smelt like. It wasn’t just the wild landscape Minnie loved, but the familiar characters she saw there. While all of London migrated to the heath in the summer, during the rest of the year you saw the same faces again and again. The regular pond swimmers were a tight-knit community in themselves, with some diehards going in all year round, cracking ice in the winter to get in.

Last autumn, Jean Finney, one of Minnie’s No Hard Fillings clients, had encouraged Minnie to give the ponds another chance. Jean swam regularly there herself, and spoke about the experience of wild swimming with almost religious reverence. Minnie hadn’t got around to it last year. Now, she had time on her hands and a newfound motivation – maybe bracing cold water would toughen her up, body and soul. She’d come for the first time a month ago. Today, the water still looked uninviting, but this time, once she was in, she soon forgot about the murk below, losing herself in the exhilarating sting of the cold and the simple pleasure of wild swimming.

Minnie thought Jean must be doing something right if she at the age of eighty-six was still swimming most days. Jean had a calm demeanour that belied a life well lived. ‘Don’t cry about something you wouldn’t cry about in five years’ time,’ she once told Minnie. ‘And swim – swim when you can.’ Those were her two pieces of life advice.