The playground at four o’clock is a machine that runs entirely on noise. Sound rises from it in a single warm cloud — shrieks and countdowns and the flat metallic clang of small feet on the slide-ladder — so that from the far gate you hear it before you see it, a kettle of pure human energy about to boil over.

Up close, the cloud resolves into a hundred separate weathers. By the swings, a girl pumps her legs with ferocious concentration, chin thrust forward, chasing a horizon only she can see; at the top of each arc she is briefly weightless, hair standing straight up, and she laughs at the sky as though she has just discovered it. Beneath her, the ground is worn to bald earth, scuffed into a shallow bowl by a thousand landing feet — a small crater carved by joy alone.

The roundabout groans on its old iron heart, over-loaded, spun by a boy too big to ride it and too generous not to push. Colours blur: a red coat, a yellow wellington, a scarf streaming like a comet’s tail. The children on board wear the solemn, glazed faces of tiny astronauts enduring g-force in the name of science.

Everywhere, focus is total and fleeting. A toddler crouches over an ant with the stillness of a monk, entirely lost, until a shout from the climbing frame yanks her attention away and she is gone, the ant forgotten, a new universe demanding her. That is the law of this place: nothing lasts, and nothing needs to. A scraped knee produces a siren of grief that, ninety seconds later, has evaporated without trace, the tears drying to salt-tracks on a face already laughing again.

The sandpit is a nation with its own economy — buckets traded, territories defended, engineering projects of great ambition and no roof. A boy pats the final turret of a castle and gazes upon his work with the pride of a pharaoh, unaware that his own foot rests, even now, upon its crumbling eastern wall.

At the edges, the grown-ups orbit like distant, patient planets, holding coats and juice and the memory of their own vanished afternoons. The low sun gilds the whole scene, throwing long blue shadows that the children ignore, being far too busy to notice such a thing as evening. And over it all hangs that cloud of sound — not chaos, though it wears the costume of chaos, but something closer to music: the pure, unrepeatable racket of small people, fully alive, entirely here.