Evenings beside Green Park, W1J and SW1A, from the Ritz corner to the Queen's Walk

The story goes that Charles II's queen, learning that her husband had picked flowers here for another woman, had every flower in it dug up. Whether or not it is true, none has been planted since. What remains is some forty seven acres of lawn and tree, striped deckchairs in summer, and a hush that seems improbable a few steps from the Piccadilly traffic.

The houses facing the Queen's Walk are among the grandest in London. Spencer House, built for the first Earl Spencer in the 1750s, looks over the park from its own terrace; Lancaster House stands at the far end, towards The Mall. Behind them runs St James's Place, a short lane with two of the quietest hotels in the city at its end.

Six hotels stand within five minutes of the park gates. They are listed so that you know where your companion is going. None is affiliated with this house, and none has been told anything.

The Ritz, W1J 9BR, is the park's grandest neighbour, with a terrace facing the trees and a Palm Court where tea is still an occasion. The Athenaeum, W1J 7BJ, further west along Piccadilly, is recognisable by the living wall of plants that climbs its front, and several of its rooms look straight over the lawns. The Stafford, SW1A 1NJ, and Dukes London, SW1A 1NY, share the end of St James's Place, a moment from the Queen's Walk.

North of Piccadilly, Flemings Mayfair (W1J 7BH) on Half Moon Street and The May Fair Hotel (W1J 8LT) on Stratton Street are each about three minutes from the corner gate. Both suit a guest who wants Mayfair's quiet southern streets behind the hotel and the park across the road.

Green Park station opens straight into the park, 1 minute from its gates, with Victoria, Jubilee and Piccadilly trains beneath. Near The Athenaeum, at the western tip, Hyde Park Corner is about 6 minutes away, a stop served by the Piccadilly line only. Some 8 minutes to the east, Piccadilly Circus offers the Bakerloo line too.

For your companion none of this applies. She comes by car, the park lies in Zone 1, and nothing is added for the journey.

In summer, some guests would rather meet outside than in a lobby. That is easily arranged: name the gate and the minute, usually the Piccadilly entrance beside the station, and your companion will be there, dressed for the evening rather than the lawn. In winter, or after dark, a hotel bar is kinder to everyone.

Octavia confirms in writing: a companion's name, the fee and the time she will arrive. She checks the hotel and the room, or the address of a residence, once. The fee is handed to your companion in person when you meet, and from then on the evening is entirely yours.

Travellers who chose a room overlooking the trees and want company at dinner worthy of the view. Guests with a few days of meetings, who want one evening with no agenda at all. Regular visitors who return to the same small hotel on St James's Place each time and like an evening to begin with a walk. The common thread is calm: an evening at a slower pace than the West End around it.

Six o'clock in June, the Piccadilly gate. Patricia, from Belgravia, arrives in something soft and pale, talks about the light on the grass the way a watercolourist would, and suggests the long way round. Down the Queen's Walk, past Spencer House, to The Mall and back up under the planes.

Seven o'clock, a table at The Ritz, whose dining room looks over the same trees from above. Dinner takes its time. Half past nine, back across Piccadilly for a nightcap on Half Moon Street. Ten o'clock, goodnight at the hotel door. Four hours, £1,800.

The closest companions live in Mayfair, just across Piccadilly: Samanta, Angelika and Luna. From Knightsbridge, two stops west on the Piccadilly line, come Sonya, calm and precise, still at the barre twice a week, and Bianka.

From Belgravia, Patricia, Violetta and Lea are a short drive round Hyde Park Corner. Violetta, tall and unhurried, is especially good company on a long walk.

Across Piccadilly, Mayfair begins with Half Moon Street and Clarges Street. Dover Street and Albemarle Street are a few minutes east, and the avenue's page covers Piccadilly itself. Through the far side of the park lies St James's, with its clubs and its lanes. Buckingham Palace and Victoria are further south, and served at the same rates.