The ponds of Hampstead Heath are small oases; fragments of wild nature nestled in the heart of north-west London. For the best part of his life Al Alvarez – poet, critic, novelist, rock-climber and poker player – has swum in them almost daily.

An athlete in his youth, Alvarez, now in his eighties, chronicles what it is to grow old with humour and fierce honesty – from his relentlessly nagging ankle which makes daily life a struggle, to infuriating bureaucratic battles with the council to keep his disabled person's Blue Badge, the devastating effects of a stroke, and the salvation he finds in the three Ss – Swimming, Sex and Sleep.

As Alvarez swims in the ponds he considers how it feels when you begin to miss that person you used to be – to miss yourself. Swimming is his own private form of protest against the onslaught of time; proof to others, and himself, that he's not yet beaten.

By turns funny, poetic and indignant, Pondlife is a meditation on love, the importance of life's small pleasures and, above all, a lesson in not going gently in to that good night.