Knightsbridge after ten: the Blue Bar, and the rooms that keep it honest

Most visitors meet the Blue Bar at seven, when it is full of hotel guests on their way to dinner and shoppers resting their feet after Brompton Road. The room is better three hours later. By ten the early crowd has moved on, conversations have dropped half a tone, and the famous colour, a soft greyish blue that seems to drink the lamplight rather than return it, is at its most flattering. It sits on Wilton Place, inside a hotel of the old school, and its small size is the point: there is nowhere for a loud table to spread and nowhere to hide from good service.

What makes it the yardstick for late drinks in Knightsbridge is not the paint, though. It is the discipline behind the counter: classic drinks built properly, glassware that arrives cold, a bartender who remembers what you ordered on Tuesday. Everything else in this piece is measured against that standard, and several rooms within a few minutes of Wilton Place meet it in their own way.

The hotel keeps a second bar, newer and opening onto a terrace, and the two make an unusual pair. Where the blue room is compact and a little theatrical, its neighbour is clubbier and warmer in tone, with a terrace that comes into its own on a mild night. Guests who spend the first part of an evening in one often finish in the other without ever setting foot on the pavement.

That is worth knowing if the hotel is your base. A companion can meet you over the first glass in blue and move with you next door once the talk has found its rhythm, and nobody at either entrance will give it a second thought. On a wet evening in November, it is the most civilised bar crawl in London: two rooms, one corridor, no umbrella.

Walk east from Wilton Place and in a few minutes you reach SW1X 7LY, a narrow house standing where Knightsbridge runs into Hyde Park Corner. Its draw after dark is music: a jazz lounge where the players keep the volume low enough to talk over, and a cigar terrace with a devoted following. For a guest who likes the late hours to come with a soundtrack, it is the obvious second stop.

A little further on, Hyde Park Corner offers two very different glasses. The Library Bar there is panelled, book-lined and hushed, with a spirits list that rewards anyone patient enough to read it. Across the junction on Grosvenor Place, SW1X 7HJ keeps its drinking at the top of the building, beside the Brooklands dining room, where the dark mass of Hyde Park and the lights of Knightsbridge spread out below the windows. One is for talking in low voices, the other for looking out, and both are a short stroll from the blue room.

In the other direction, Knightsbridge runs past SW1X 7LA, whose bar faces the park through tall windows, and The Aubrey inside the same building, a moodier room with Japanese cooking and a long list of sake for anyone who wants something less traditional than a martini. A few steps beyond, turning into Raphael Street brings you to Zuma, the one address in this piece that genuinely hums late on a Friday: good music, a well dressed crowd and cocktails taken seriously.

Zuma is where Molly likes to open a later evening. One of the curvaceous portraits, she knows her house music, treats a good bartender with the respect other people save for a surgeon, and by eleven she will have half the counter joining the conversation. It is the right choice for a night that wants energy. For a night that wants hush, stay east of Sloane Street.

The simplest way to plan a late drink here is to settle the mood and let the company follow. For the blue room itself, Danielle remains the classic pairing, dark haired, slow spoken and happiest in a corner with something stirred; she belongs to the raven haired set, whose looks suit the low lamps of these hotel bars rather well. For the park windows at SW1X 7LA, Sonya brings a dancer's composure and a way of listening that makes the day's noise fall away.

Michelle, who invents cocktails for fun and always takes the seat facing the door, is excellent company on a crawl of two or three stops. Karolina, dry witted and fond of architecture, will tell you which of these buildings is older than it looks and who put the columns there. If you would rather not choose at all, describe the evening to Rosie and she will come back with two names who fit it.

An hour, at £400, is the natural length for one bar and a proper conversation. Ninety minutes, at £600, lets you take in a second room, perhaps the blue room followed by the jazz at SW1X 7LY. Two hours, at £750, covers a drink downstairs and a quieter stretch back in your suite. When the night is built around going out rather than staying in, the night out commission is shaped for exactly that, and the rates page lists the whole ladder, length by length.

Tell Rosie which bar you will be in and roughly where you are sitting. Your companion messages as her car pulls up, walks straight to your table and orders her own drink as any guest would. The bar bill stays with you as host; her fee is settled with her privately, in person, and never across the table. If the room is full when you arrive, send Rosie the name of the next bar along, and the evening simply moves with you.