London’s glossiest townhouse

Despite there being no obvious sign to indicate you’ve arrived at …At Sloane, I sillily laughed at myself when I spotted the very friendly and smiley doorman outside the real entrance, there to happily help with your bag and ask how you are as you climb up the few stairs to the double doorway. 

Nearby, the Saatchi Gallery continues to draw in the cool art crowd, while a long lunch at the bar at Colbert still leads as one of the best meals out in London – the chopped chicken salad, once a Corbyn & King mainstay. More recent food openings include the much-talked-about Italian restaurant Martino’s, where Tom Ford sunglass-wearing diners sip frosty martinis and eat zucchini fritti with surprising speed.

…At Sloane truly sits perfectly poised between these worlds – the hotel claims a former townhouse, and as a result, it feels as though you've wandered into a terribly smart private house belonging to a well-to-do friend. The three-year-old hotel belongs to the Costes family – the hospitality dynasty behind some of Paris's most seductive addresses – and discretion is a big part of the brand's DNA. 

There is no conventional lobby – a concept I often struggle with, as it’s hard to know where to go – but instead, I welcomed the sight of a small team set up, tapping away on laptops around a strikingly long black table dressed with carefully arranged coffee-table books and fresh flowers, all poised at the ready to greet whoever walks through the door.  

I fell in love with the design: the trompe-l'œil ceilings, intricate wrought-iron detailing, hand-painted finishes and seemingly endless yards of Loro Piana fabrics; it's difficult to imagine expense featured heavily in the conversation (for the better, because look at it!). "We'd be nothing without the design," a member of the team tells me, pointing out all the remarkable choices that might have gone amiss if you didn’t know what you were looking at. 

Designed by François-Joseph Graf, every millimetre has been thought out – from the floor pattern that runs down the stairs in slick alignment and the Ateliers Loire Chartres stained-glass windows that cast jewel-like light across the corridors, to the Arts and Crafts-inspired flourishes across each floor and the light switches in the room (one for love, one for sleepy time, one for music from the Costes playlist). Graf took his cue from Chelsea itself, particularly the magnificent brick architecture and narrow proportions of Cadogan Square. He also travelled to the Smithsonian in Washington, DC, to measure the Peacock Room, the extraordinary Victorian interior by James McNeill Whistler, as inspiration for the restaurant. “I designed all the curtains myself,” he says, and they vary from room to room, borrowing from Viennese art, Arts and Crafts and Neo-Greek styles.  

My room was incredibly beautiful – with not one, but four separate spaces for sprawling (a deceptive amount of space for what, from the outside, looks like a tight townhouse space; it most certainly is not). The same window shading was applied here, but what I really loved was the turreted room for the his-and-hers sinks. 

Upstairs, the sixth-floor restaurant might just boast one of the most beautiful dining rooms in all of London – white tablecloth-covered tables sit beneath soaring ceilings, where big double doors flood the room with soft light and grant access to a much-welcome balcony, while carefully placed (by Graf himself) porcelain vases flown in from Singapore claim every inch of the walls and shelves. The menu leans towards Costes classics – a very sweet-and-salty miso salmon arrived perfectly cooked with sautéed spinach, while an absurd (I’m not complaining) mountain of shoestring fries proved impossible to stop eating. 

“What truly connects Hôtel Costes in Paris with …At Sloane is the meticulous attention Jean-Louis has always paid to the proportions of his furniture. To make spaces feel larger, he had the wonderfully clever instinct to lower the height of both chairs and tables, making any dining room much more convivial. As a result, the dining room feels immensely spacious, and the walls of the bar seem to disappear in turn,” Graf says of the room. It sounds like a small trick, but it makes total sense when you’re sitting down.

Downstairs, however, is what reminded me exactly why this brand stays relevantly buzzy. Behind a separate entrance on Holbein Place, the basement bar operates almost as its own party-happening world. On the evening we slipped in, it was packed with designers, entrepreneurs and impeccably dressed couples. Within moments of giving our room number, we were whisked towards a low-slung table by an incredibly smooth host who greeted me by name and delivered one of the best Negronis I've had in a while. It's a small detail – a name greeting, a table at the ready for staying guests – a touch that’s increasingly rare in hospitality and always remembered. 

That's the Costes magic; it mixes the best of the bunch into one shared space for good times and proper service. “Yes, while Chelsea is about culture and the arts, the hotel is definitely about having a lot of fun,” as one member of the team put it. …At Sloane channels that sentiment perfectly – it may present itself as exclusive and terribly well-behaved from the outside, but beneath the brickwork and cashmere curtains lies something much more entertaining. And there may be more to come: Graf hints that if the adjoining building becomes available, there is scope for the hotel to grow – with more suites, a gym, spa and swimming pool all on the wish list.