A room full of colleagues, and a companion who reads it correctly

The briefing, in five lines

Write Delphine the name of the event, the dress, the hour, how you would like the two of you to be understood to know one another, and anything that must not be discussed. Five lines is generally enough.

Your companion reads it once, writes nothing down, and does not look at the thread again. If somebody at the table asks her what she does, she answers with something dull and entirely plausible, and the subject has moved on before you have finished your drink.

How the evening runs

Most guests meet her half an hour before the event, at a bar a short walk away, so that the account of how the two of you know one another is agreed over one drink rather than rehearsed on the pavement. The reception usually runs to forty five minutes, during which she stays at your side unless you move off to speak to somebody alone. Dinner takes two hours and the speeches another half, and the cloakroom is where most of these evenings reach their natural end. Four hours at £900 covers all of it with a little room to spare.

Dress and the seating plan

Tell her the code and she meets it exactly: black tie, lounge suits, or the awkward middle ground most trade dinners occupy. She dresses a shade under the room rather than a shade over it, which is the correct instinct and not one everybody has.

If the plan separates the two of you, she is perfectly capable of two hours between a chief executive and somebody's spouse, and she will be better company than either of them expected.

Where these evenings happen

The ballrooms and private dining rooms of Park Lane take the largest of them, with the smaller dinners going to the panelled rooms behind Berkeley Square. The private rooms of Dover Street and Albemarle Street take the most discreet of all, where a table of twelve counts as a large one. A conference dinner at an airport hotel is arranged differently and quoted at a longer length, since her travelling time is counted inside it rather than added on afterwards.

Discretion, which is the whole point

She does not photograph a room, and she will step out of anybody else's photograph without making a moment of it. She takes no telephone out at the table. She keeps to one glass at a working dinner unless you have said otherwise, and she leaves with nobody but you. None of this has to be asked for. It is simply the way this circle works a room.

Names for a formal room

Danielle is the most composed woman here and will talk about a building for an hour with real pleasure. Violetta is formal, plain about what she wants, and needs assistance from nobody in any room. Patricia is exacting and very funny about being exacting. Margo gives complete attention and has a memory that never needs reminding. Read them in the Salon and give Delphine the date.

When the event changes

Receptions move more often than dinners do. If the start is put back, one line to the switchboard moves her arrival with it, and her hours still begin when she reaches you. If the evening is cancelled with three hours of warning or more, nothing is owed; inside two hours, half the agreed figure stands. If the seating plan changes on the night, she manages wherever she is put and says nothing about it.

Afterwards

Most of these evenings finish at the cloakroom, and that is a perfectly good ending to one. If you would rather the night carried on past the reception, ask for the longer length when you book it rather than on the night itself, since a diary is far easier to open in advance than at eleven o'clock.