Hotel visits, the shortest ride from your message to your door

Write to the desk over WhatsApp or Telegram: the girl you have in mind, the hotel, the hour and how long you would like. An answer comes back within minutes. Before anything is fixed we check three details once, in that same chat: the full name you are staying under, which hotel, and your room number. They travel no further than the desk and your companion. A 25 percent bank transfer then holds the visit, and when she leaves home a short note tells you she is on her way. The whole sequence is laid out on the booking page for anyone who likes to read before writing.

Nobody at a good London hotel gives a second thought to an elegantly dressed guest crossing to the lifts late in the evening, and our companions keep it that way. She dresses as a guest meeting a friend for a drink would: a tailored coat, quiet heels on the marble, nothing that begs to be noticed. If the lifts need a keycard, come down and meet her, or tell the desk and she will wait in the bar until you do.

From the revolving doors of The Langham on Portland Place, the Corinthia just off Whitehall or the Royal Lancaster looking over Hyde Park, the walk up to your floor takes three minutes and leaves no trace in anyone's memory.

One hour holds a drink, a real conversation and a gentle close to a long day. Ninety minutes lets the evening breathe, perhaps with a glass downstairs before going up. Two hours is where most first bookings settle, because neither of you has to glance at a watch. Three hours leaves space for room service or a short supper round the corner. Beyond that, a dinner date or the night rider overnight usually describes the evening better.

Angelika lives in Mayfair and saves her evenings for the hotels between Piccadilly and Park Lane, with Berkeley Square in the middle. She is athletic and 172 cm, with long straight black hair and a wit that arrives before you see it coming, and she sits among the raven haired girls. Michelle and Stacy both live in Chelsea, which keeps Sloane Square and South Kensington minutes away. Michelle, tall and curvy with long dark brown hair, confirms fast on most nights, while Stacy, slim at 176 cm, will gladly say yes at nine to a ten o'clock start.

Tina, toned and petite in stature at 158 cm, covers the Strand and Covent Garden at short notice. Laura, green eyed with sun lightened brown hair, is ready from midday for guests who have just stepped off the Heathrow Express.

Not every London night is spent in a hotel. A townhouse in Belgravia, a flat above the shops on Marylebone High Street or a serviced apartment in Kensington is visited in exactly the same way, with the address confirmed once over WhatsApp in place of a room number. Mention a concierge, a buzzer that hides from strangers or a mews entrance tucked round the back, and she will arrive without having to ask a soul for directions.

Someone is on the desk all night, so a message sent at half past two is read as promptly as one sent at seven. Late visits keep the same fares and the same checks. The only thing that changes after midnight is the traffic, which grows kinder: the ride from Chelsea to a hotel on the Strand is often quicker at three in the morning than at six in the evening, when the Embankment is still nose to tail.