Margo has the quietest presence on this list and the most durable one. Slim, 166 cm, hair long and dark brown and straight, and brown eyes that land on you and stay. Early thirties. Her clothes are restrained to the point of being invisible in a photograph and obvious in a room: good cloth, no logos, one bracelet she never takes off. She gave up dressing for attention some years ago in favour of dressing for comfort, and it works far better.

English, and she is an excellent conversationalist in the old sense, which means she is mostly asking. She has no interest in impressing anybody and that turns out to be disarming. She swims in cold water, reads history, and has spent enough time in Knightsbridge to be entirely unimpressed by it while still enjoying every bit of it. Very little in this city surprises her now, and she likes it better for that.

Her SW1 evening is dinner at Mr Chow on Knightsbridge, the long white room that has fed the same sort of people the same dishes since the sixties and has never felt the need to change. She sits with her back to the room. Knightsbridge is her home district, so when dinner ends she can tell you which hotel bars along the road are still worth an hour and which have been coasting for a decade.

Nothing before 6 October, though the desk is already holding evenings after it. The Knightsbridge page runs through SW1 and the women who work there. Name a night and a hotel to booking and you will be given the first evening she can actually do.

Nothing has been written up under Margo yet, which is usually what discretion looks like. A note goes on the board only when a client sends one in writing, she agrees to it, and the office has checked that it reads as a first name, a month and nothing private.