On a sunny south London morning in March 2008, on a leftover piece of urban land – a brownfield site in the planning jargon, but one long since colonised by playing children – there is an unusual spectacle.

Four middle-aged men in suits and ties are swinging, two of them in tandem, in long, high arcs. Clinging for all they were worth to thick, sturdy lengths of rope suspended from homemade, brightly painted wooden structures made from old telegraph poles and assorted planks of scrap wood, the men appear tentative at first, clumsy and ungainly in their buttoned up shirts, shiny shoes and politician manners. It seems certain that one or more of them will lose his grip; crashing his bones, dignity, and very likely his career into the rubble and nettles below. There are no safety surfaces here.

Gradually, though, the men’s confidence visibly increases as they seem to recall long-forgotten skills. Nervous pleasure turns to something close to unrestrained glee; they begin to enjoy themselves. Concentrated on the physical immediacy and real challenge of these monster swings, they become lost in the moment. For a few minutes these serious, powerful men forget how important they are and what they might look like in the newspapers the next day. They remember how to play.

More grown-up looking people, about 30 of them, equally unsuitably attired for the ramshackle environment in which they find themselves, take photographs and videos, make notes on clipboards, look anxiously at watches, speak over-excitedly on mobile phones or just look on, nervously. A group of children marched in for the occasion from a nearby primary school wait on the periphery looking bored. Still the men play on their swings, laughing now and egging each other on until, anxiously, one of the onlookers gesticulates that they should stop. It is time to get on with the business of the day.