Those who’ve visited Paris’ Hotel Costes, perhaps to stay in its boudoir-like rooms or imbibe in its impossibly glamorous restaurant and bar, will know the feeling it evokes – the glamour, the slight naughtiness, the feeling of true seduction and hedonism. The hotel is one of the most iconic properties in the City of Light, and now, the hotelier behind the legendary offering has opened a new property in London: One Sloane.

Seven years in the making, famed hotelier Jean-Louis Costes’ new offering has finally opened its doors, and one thing is clear: you can’t rush perfection. Quietly opening its doors in September, the property invites guests into a heady mix of Parisian flair and craftsmanship with British heritage and charm, with just 30 bedrooms, a secret basement bar and a brilliantly white restaurant. Here are 9 things to know about London’s chicest new hotel, One Sloane.

The location is the best of both worlds

Quietly opening its doors In September, One Sloane resides on a leafy street in London’s affluent Chelsea neighbourhood, hidden away in a 19th-century red brick mansion block with just an impeccably dressed doorman as a giveaway. While peaceful and discreet, the property lies just off Sloane Street and a short walk to London’s luxury shopping hotspots like Harrods, Harvey Nichols and King’s Road, as well as the cobbles of Belgravia.

The building is full of history

One Sloane has taken up residence in a typically Chelsea red brick Victorian mansion building, and, while conceived by Costes, is the work of Cadogan Estates – Chelsea’s largest landowner – and French designer François-Joseph Graf. The building was designed in 1889 by architect Edwin Thomas Hall (the man behind Liberty of London and Dulwich College library), and today’s facade has been given a grand makeover to restore its original Victorian shine. As expected, serious renovations were in order, including the addition of a sixth floor and a lower bar level – where the full Paris experience will not likely be experienced.

It’s incredibly exclusive

London has no shortage of boutique hotels with very few keys, but One Sloane feels even more exclusive – largely down to its discreet location and top hotelier credentials. There are just 30 bedrooms and suites, designed to offer the emotional intimacy of a private residence and feel more like a chic Parisian apartment than hotel room. Each room – decorated in soft, warm and bright hues – comes complete with restored antique furnishings, period wallpaper and features playful trompe-l’oeil.

There are six categories of rooms to choose from, including the ultimate Chelsea apartment

Despite having just 30 rooms, guests can book into six room categories – from the cosy Mini (an intimate 18sqm Chelsea bolthole with a Queen-sized bed and shower) to the sumptuous Apartment Sloane – an enfilade of rooms sleeping four guests with two bedrooms, two bathrooms – plus a soaking bathtub- living area and walk-in wardrobes. Other rooms include the 22sqm Essentiale, 30sqm Chelsea, 38sqm Chambre Sloane and the 46sqm Suite Sloane – each reminiscent of a private boudoir clad in soft, creamy tones with design details like velveteen sofas, lack-and-white vintage photographs and restored antique furnishings, plus signature stained glass windows and mosaic-tiled bathrooms.

Interiors marry British heritage with Parisian elegance

The hotel is led by interior design, and Graf not only marries French with British but includes accents inspired by the British Empire at the turn of the century. To tell the story of bygone grandeur, antiques were sourced from across the world, in Singapore and Hong Kong, Calcutta and Sri Lanka, Cairo and Baghdad, and walls were dressed in William Morris wallpaper. Matching the grand exterior, guests enter into a spectacular white neo-Greek lobby. They can enjoy touches like stained-glass windows, a striking mosaic floor and colourful Anglo-Chinese vase displays.

The building was carefully restored

As part of the six-year project, Graf collaborated with the best British artisans and French craftsmen to bring the historic property back to its former glory. Original period details such as ceiling cornices, stained glass windows and wood panelling were restored, with restored antique furnishings and playful touches like trompe l’oeil and rich textures and fabrics. Lighting was also key – and the property has been carefully illuminated courtesy of heritage lighting consultant Jeremy Quantrill, who reproduced light fittings from over 50 original pieces.

There’s a seductive bar for those in the know

Much like Hôtel Costes, One Sloane will have a speakeasy-type bar tucked away from sight and embodying the hedonistic spirit of the property. Through its own private entrance on Holbein Place, guests will be able to step into a seductive world with a soundtrack curated by the hotel’s in-house DJ. The bar is open now from 6 to 11pm and is set to be the chicest neighbourhood hangout for those in the know.

The restaurant transports guests to Paris

Ascend the grand staircase from the Neo-Greek lobby to the first floor, and you’ll find an elegant all-day restaurant. The spectacular white space serves simple French cuisine with the best quality ingredients, bathed in dazzling natural light – thanks to the elegant stained-glass windows – and with the hotel’s signature monochrome mosaic floor. Design touches pay homage to the Victorian Chinoiserie trend, such as display shelves featuring a curated collection of Chinese vases in the same monochromatic tones.

Doubles from £600 a night (about AED2,700); onesloane.co.uk