Chic and unique: Fashion designer Maria Grachvogel's London home is full of bold feminine touches

Maria Grachvogel's urbane apartment, high above the rooftops of Marylebone in central London, wouldn't look out of place in an old Rita Hayworth film. It is a decadent, sensuous pleasure dome littered with undulating, curved chaises in hot, lipstick reds and inky purples and the bold, colourful, yin and yang nudes of the Danish artist Charlotte Valeur. This is not surprising when Grachvogel's clothes designs are all about tactile velvets, silk satins and gossamer cashmeres which cleave and flow over the body in all the right places. Her clothes - while never being too outre - are essentially all about sex, sensuality and feminine power.

"I think I work in quite a strange way," she says. "I don't follow trends. It's not about a look or a perspective. It is about creating a mood. What I try to distil is the inner feeling of being a woman. I am interested in creating architecture for the body and I guess my home is an extension of that. It is all about an appreciation of colour, form and shape." Maria is certainly the perfect chatelaine for this intimate, playful West End eyrie. Every night she comes home in anticipation that Mike, her boyfriend who is a banker in the city, will be playing the black Steinway when she walks through the purple door and kicks off her heels.

Their home is a reflection of a shared love of art, music and sleek simplicity. The couple stumbled across the flat a decade ago after searching fruitlessly in Kensington and Chelsea for a loft-style space. Marylebone wasn't fashionable then. "It didn't have all those palaces to cheese! In fact, it hardly even had a supermarket," says Maria. "The building stands out because it's a 1950s purpose-built block surrounded by 19th-century stucco townhouses. The site was bombed during the Second World War and when we came along, it was very dated and dark and the builder who owned it offered to refurbish it for us and put carpets everywhere. We said no, don't do anything. We could see the potential and we just fell in love with it and bought it as a shell."

They spent the next two years working with a very accommodating firm of builders to take down the internal walls, creating an open-plan living room and sleek kitchen where they could cook together, relax and entertain - all in one huge, airy space which flows from the sleek stainless-steel kitchen to the oversized Intermura sofa.

The end result is an interesting marriage of clean lines and splashes of bold sensuality. As a space, it is both meditative and mercurial in personality. The white walls and bleached-blonde wood floors evoke a feeling of serenity, light and space, which is suddenly punctuated - thanks to an impromptu trip to Paul Smith Home - by a fire-red Pierre Cardin sideboard and calfskin coffee table. Her love of natural forms is clearly on display, most dramatically evidenced in the over-sized glass and iron dining table which sits on a central bed of entwined iron branches. Maria designed the table while on holiday in Bali. "We had it shipped at huge expense to London and then it took four people to bring it up the stairs. It is a beautiful piece and so heavy; we can't move it." The matching chairs are covered in richly textured silk velvet cushions the colour of amethyst. They are made from the same velvet as Maria's bias-cut evening gowns which fly out of her Sloane Street shop. "Being a designer is useful. I always seem to know someone who can run things up for me. The cushions were made by a family friend who has her own soft furnishings company."

Even the limited-edition champagne bottles from Moët and Chandon which sit on the bar are dressed for the occasion. Bejewelled with a hundred, twinkling Swarovski crystals, they were a gift last Christmas. "I don't think I will ever open them; they are lovely just to keep and admire." Then there is her beloved Himalayan cat Pasha, a gorgeous, shy and retiring puffball of chocolate and cafe au lait who goes to ground under his mistress's bed until the interlopers have gone.

It is late morning, but Maria wafts around the apartment, dressed as if for the cocktail hour in her signature sinuous-black, silk-crepe catsuit, slashed to the waist in a dramatic, deep V and sky-high Balenciaga wedges. I have to ask. Is there a risk that the wearer will reveal more than she might want to? "No!" laughs Maria confidently. "That is the point. My designs promise more than they reveal. It is all in the cutting and the tension. The V stays put. But the suggestion is there, that it might show more than a glimpse of decollete - that is the tease."

A gleaming white staircase to the upper floor provides the perfect foil for an oversized, original poster of the kind of woman who might sashay through the doors of Maria's Chelsea boutique. She is a confident, crimson-lipped fashion maven from the Thirties - dressed in a hat and furs. The one thing Maria doesn't do is understatement. "It's true," she says, her blue eyes glittering. "I only know how to be very glamorous. I have even schooled myself to run to the office in four-inch heels."

Maria loves to have space to move around and the master bedroom reflects her passion for drama, opulence and an absolute lack of clutter, unless you count the scratching post for the cat, sitting incongruously by the window. It is a wonderfully homely touch. Tamara de Lempicka's woman in green gazes mysteriously over the emperor-size bed, which is covered in a shimmering, devore throw and a giant purple-cube daybed adds a flamboyant note to a room devoid of superfluous knick-knacks. In the corner of the room by the window sits a very special, vibrant green leather chair.

"It was the first piece of furniture I ever owned," says Maria. "I had just left home and moved into my first flat and all I had was a bed. I went to a Christmas party and someone was calling out names and I won a chair. One moment I didn't have a chair and then I did. How great is that?"

There is something of Casablanca in the backdrop that Grachvogel has created - the glassy, black Steinway grand and her own cocktail bar where she likes to put her mixology skills to good use. She's even invented a cocktail called "The Grachvogel": take three cubes of rock brown sugar; half a fresh lime; one fresh passion fruit; one measure of Cachaça, some crushed ice, then muddle and serve. "One day, maybe Mike and I will retire and open a bar and I will get to waft around in a catsuit dreaming up cocktails and listening to Coltrane," she says with a faraway look.