Park Lane, W1K, where a booking is measured in nights rather than hours

The hotel row runs from Hyde Park Corner up to Marble Arch, and a companion knows every one of these entrances and which lift goes where. These are addresses, not partners. Nothing has ever been agreed with any of them, and nothing needs to be.

The Dorchester, W1K 1QA, sits behind its own forecourt halfway along. Facing it across the road, smaller and quieter, is 45 Park Lane, W1K 1PN. London Hilton on Park Lane, W1K 1BE, is the tall one, and the view from its upper floors is why people book it. Grosvenor House, W1K 7TN, holds the northern end. Two more sit above the Corner: InterContinental London Park Lane, W1J 7QY, and then Four Seasons Hotel London at Park Lane, whose W1J 7DR is as grand as its name.

A suite on this road has a sitting room, and a sitting room changes what an evening can be. A drink can be had somewhere that is not a bar, food eaten somewhere that is not a restaurant, and there is a window worth standing at. Guests who have taken one of these for a week rarely want an hour of anything.

Arrival is the other reason. Long flights land into the evening, and a guest who reaches his room at ten has a night in front of him and no appetite for a dining room. Ten hours covers that properly: a late supper sent up, a long conversation, sleep, and a morning nobody has to hurry through.

Hyde Park Corner sits 3 minutes from the southern end, Piccadilly line. Marble Arch, Central line, is 5 minutes from the northern. Green Park, with Jubilee, Piccadilly and Victoria trains, is 8 minutes east through the streets behind.

The road itself is wide and quick, and crossing it on foot is less of a pleasure than it looks. Arrivals here are by car at the front entrance, which is simpler at every hour and unremarkable at all of them. Journeys within the first two zones are covered; past them, the return fare is quoted alongside the hour.

An overnight carries a start hour and a finish hour, both written down. Eleven until nine is what most guests here choose, and Octavia will say frankly whether the finish you want is realistic for the companion you have picked. What she packs is for the morning, and none of it needs explaining at a desk.

Confirmation runs to three items: full name, house, room number. She walks through the main entrance like any other guest, that being the least interesting way to arrive. The figure agreed passes to her at the door, once, and is never a topic afterwards.

Guests on long stays, whose diaries are full until nine at night and empty after it. Travellers between one city and the next, in London two days and disinclined to spend the evenings on a laptop. People attending something large in one of the ballrooms, who would rather walk in beside somebody than alone. The request is for a companion who is easy across an entire evening, not merely across its first hour.

Half past nine. A guest lands, reaches a suite at The Dorchester, and writes from the car: an overnight from eleven, and please somebody who will talk about anything other than the flight he has got off. Octavia proposes Margo, who is calm, low voiced, and good at the hour when nobody wishes to be entertained.

Eleven o'clock. Supper arrives upstairs. They discuss a saleroom lot she had views on and he had never heard of, then nothing in particular, then not at all. In the morning there is coffee by the window with the park turning green in the light. Ten hours, £3,000, and a car at nine.

Samanta, Angelika and Luna are Mayfair residents, five minutes behind the road on foot. Margo and Sonya come round the Corner from Knightsbridge. Patricia travels from Belgravia and Liana from Marylebone, each about ten minutes at that time of night.

For an overnight, Octavia will steer you towards the women who genuinely enjoy them. It is a question of temperament rather than stamina, and she knows which is which.

Northward the road meets Grosvenor Square and the streets behind it. Eastward lie Mount Street and the rest of Mayfair. South, past the Corner, Green Park opens along Piccadilly, while Knightsbridge is five minutes the other way round the roundabout. Terms hold across all of them.