The entrance immediately reveals the unique ambience of this creative place where audacity rules. The dark vestibule, painted in Railings – a soft black with blue undertones by Farrow & Ball – contrasts with the rest of the bright rooms.

The space features an antique stove in ceramic and brass from the end of the 19th century, a Michael Anastassiades IC Ceiling Light for Flos and a pair of bronze Pulcinella wall lamps made in 1987 for the Lacroix Haute Couture Salons by Elizabeth Garouste and Mattia Bonetti.

Other statement pieces include a folding screen embellished with 17th-century Dutch embossed leather panels that was designed by Sacha and manufactured by Karen Mourra, as well as a Fur Play armchair in brass and steel, another Sacha creation in collaboration with French ornamental metalworking firm Pouenat for Galerie Gosserez.

“Pieces of art and design are placed here and there and might be moved from time to time to keep the energy vivid,” Walckhoff says. “Moving furniture is great therapy!”

A wall of curiosities – ranging from a vintage anatomical sculpture to artisanal ceramics – awaits visitors.

The square living room, which has 19th-century architectural details and a French fireplace in Carrara marble, features a mix and match of antiques, modernist and contemporary pieces of art and designs that pop against the white background.

A Knotted Chair by Marcel Wanders, a vintage Model 498 beige tweed armchair by Pierre Paulin, a burnt oak and copper console table by Valentin Loellmann for Galerie Gosserez, a Janette Laverriere brass floor lamp from the late 1940s, a steel bench – an original piece made for Air France’s first-class salons in the 1970s – by Maria Pergay, a three-legged Charlotte Perriand chair, Mathieu Mategot 1950s side tables and shelves, and a green chair by Maarten Baas are some of the many furniture pieces in Sacha and Pascal’s collection.

“Surrounded by shelves and archive boxes, the studio can be extended into the dining room table for big meetings and projects,” explains Walckhoff. In the bedroom, the couple wanted the feeling of being in a library.

“We both love to spend hours in bed while in the middle of our books and documentation, looking for inspiration and exchanging ideas,” he adds. A light green hue – a nod to 18th-century boudoirs – was chosen for the bathroom.

“Pascal was specific about this. We finally found this Cooking Apple Green at Farrow & Ball,” says Walckhoff. “It is an amazing colour to start the day with. The bathroom is facing south, so the colour is truly radiant. Its style is rather simple but sophisticated, like the easy luxury of small Swedish castles.”

Conceptualised as a multifunctional space, the apartment highlights Sacha and Pascal’s extensive collection of art and design objects that are “displayed in our way”, according to the designer. “It is eclectic and unique but with a strong Parisian flavour and a little bit of humour.”