Five hundred years ago the notoriously savvy Henry VIII discovered an elegant way to solve both his theological problems and his personal liquidity crisis—he dissolved the monasteries and nicked all their land. Since the principle of any rich person who wants to stay rich is, Never give anything away unless you absolutely have to, the land has stayed with the Crown ever since. Three hundred years later the prince regent hired Nash to build him a big palace on the site with some elegant terraces that could be rented out and thus cover the prince’s heroic attempt to debauch himself to death. The palace was never built but the terraces and debauchery remained—as did the park, which bears the prince regent’s title. One end of the park, the Northern Parklands, is given over to playing fields and sports facilities and at the center of those sits the Hub, a large artificial hillock with a pavilion and changing rooms built into it. It has three main entrances built in the manner of aircraft dispersal pens that make it look like the ground-floor entrance to the lair of a super-villain. On top is a circular café whose Perspex walls give a 360-degree panorama of the whole park where customers can sit, drink tea, and plot world domination.

It was still sunny but the air was taking on a warning chill. In August the crowd spread out in front of the temporary stage and lounging on the concrete apron that surrounded the café would have been half naked. But by mid-September sweatshirts had been unwrapped from around waists and sleeves pulled down. Still, there was enough golden sunlight to pretend, if only for another day, that London was a city of street cafés and jazz in the park.

The current band was playing something fusiony that even I wouldn’t classify as jazz, so I wasn’t surprised to find Tista Ghosh nursing a white wine beyond the refreshment tents where the noise would be muffled. I called her mobile and she guided me in.

“I hope you’re buying,” she said when I found her. “I can’t make this Aussie fizz last much longer.”

Why not, I thought. I’ve been getting them in all week, why stop now?

Ms. Ghosh was a slender light-skinned woman with a sharp nose who favored long dangly earrings and kept her long black hair tied back in a ponytail. She wore white slacks and a purple blouse and over that a gentrified biker’s leather jacket that was at least five sizes too big for her. Perhaps she’d borrowed it against the chill.

“I know what you’re thinking,” she said. “What’s a nice desi girl like me doing in the jazz scene?” Actually I was thinking where the hell she’d got that leather jacket and should she, for religious reasons, be wearing a leather jacket in the first place.