Escorts in Hyde Park, W2 and W1K, with the Serpentine going silver at dusk

The Serpentine cuts the park in half, with the bridge across the middle and a bar and kitchen on the eastern shore where the swans are entirely unafraid of your chips. On the southern bank the memorial fountain to the Princess of Wales runs as a shallow oval of moving water that children paddle in all summer and nobody photographs well.

Rotten Row runs along the south side, a wide sand track laid for riders that still carries horses most mornings and is the single best place in central London to walk at seven in the evening. At the north west corner the Italian Gardens hold their fountains and urns above the Long Water, and two galleries sit on either side of the bridge, one of them in an old gunpowder store with a curving extension bolted on.

The eastern lawns change with the calendar: deck chairs and a bandstand in summer, a full fairground with wooden huts and ice for a few weeks in winter. The park closes at midnight and opens at five, which is worth knowing if your evening plan involves a shortcut.

Two kinds of guest, and they arrive from opposite sides. On the Bayswater and Lancaster Gate edge the rooms are big, the views are long and the guests are often here for several nights with family arriving later in the week. On the Park Lane and Knightsbridge edge the rooms are smaller, older and dearer, and the stay is usually two nights on the way to somewhere else.

What they share is the wish to stay put. A guest who has paid for the view does not want to spend the evening in a taxi, which makes the park perimeter the easiest geography on this site to plan. Dinner in the hotel or three minutes from it, a walk while the light goes, and a bar with a window. Three hours, £1,050, is what most guests around this park end up choosing.

On the north side, W2 2TY stands tall enough that the upper floors look clean across the treetops to the far shore, and W2 4RJ sits a few minutes west on the Bayswater Road behind a Victorian front. Around at the north east corner, W1H 7DL takes the Marble Arch junction.

On the eastern edge, W1K 1QA faces the park across Park Lane with its gilded promenade and a terrace above the traffic. At the southern corner SW1X 7LA and SW1X 7TA look north into the trees from Knightsbridge and Hyde Park Corner respectively, the first with the best park facing rooms of the six.

All six are places on a map. Nobody around this park has any tie to this magazine, and nobody behind a desk is ever told who is arriving or why. She gives your name in the lobby, or rides up alone provided Bella has been handed a number and the name the stay was booked in.

Four stations ring the grass. The northern gates are served by Lancaster Gate, about 2 minutes away on the Central, and the north east corner by Marble Arch, roughly 3 minutes off on the same line. Down on the Piccadilly, the south east gates sit 3 minutes or so from Hyde Park Corner and the southern edge some 5 minutes from Knightsbridge. Which of them matters depends entirely on which side of the grass your window faces.

A car delivers her round the perimeter, its first two zones priced in at the quote, which is why the number never grows. A same evening booking anywhere on this ring normally sees her about an hour after confirmation, longer when the Bayswater Road or Knightsbridge is backed up, and the exact time comes through in the chat as she sets off; a booking arranged in advance keeps the hour it was given. She takes her fee from you as she comes through, and the room had been set down in writing first.

Laura still talks about this one. A guest on a high floor at W2 2TY, three hours from half past five in September, who said on the phone that he had been in London four days and seen nothing but a conference room. Sun streaked hair, green eyes, an unreasonable amount of energy.

She walked him down through the Italian Gardens to the Long Water, along to the bridge and out onto Rotten Row while the sky went from gold to grey, talking the whole way about a road in Italy she still means to drive. They got back up to the bar with the window at twenty past eight. Three hours, £1,050, and he changed his flight.

Paddington is home to Laura, Nora and Vanessa, just beyond the northern gates, and all three know this park at every hour it is open. Bianka and Margo come from Knightsbridge on the southern edge, one for the wine list and one for the late hours.

Angelika and Luna cross from Mayfair, Angelika usually having played tennis somewhere that morning and Luna with a camera she still loads by hand. Seven names around one park, which makes this the postcode where a last minute booking is least likely to disappoint.

East across the traffic runs the hotel row of Park Lane. South at the Corner lies Knightsbridge and the shops. North east, three minutes from Speakers' Corner, is Marble Arch, and behind the eastern railings the streets of Mayfair begin.