Before I met the Italian fashion designer Veronica Etro, I had made all sorts of presumptions about what she would be like. I had assumed she would be spoilt (her family company turned over £209 million from its 120 stores in 2006). That she would be a fashion victim (an affliction that often strikes those who make their living from devising new trends). That she would be aloof (her parents are extremely press-shy). That she would live in an interior-designed pad, stuffed with designer furniture (she is stylish and Italian). And that she would be as away with the fairies as her press material, which describes her mythical muse for her 2008 Kaleidoscopic Woman collection as someone who “lives under the sea, immersed in a luminous Atlantis of the future”.

I was wrong on all counts. Like her three older brothers, Ippolito, Jacopo and Kean, with whom she runs the fashion business set up by their father in 1968, Veronica appears to have none of the flaws you would expect. The 33-year-old is polite, warm, sweet, charming and even a little shy, as she shows me round the three-bedroom, four-floor Milan house she shares with her lawyer husband, Alessandro, and son, Filippo, 3. She is wearing jeans, wedges, a cardigan and a dab of plum lipstick.

“When I was trying to find this house, after I’d finished Saint Martins [fashion school in London], I was living with my parents, and knew that what I wanted was nothing like what they lived in,” she says. (Mama and Papa Etro live in what can only be described as a cross between the British Museum and Buckingham Palace, filled with antiquities and an extraordinary collection of art from De Chirico and Francis Bacon to Raphael.) “I didn’t want to be worried about whether I was going to break something, or forget to put on the alarms when I went out. I wanted it to be light and modern, somewhere I could relax. So this was perfect.”

When she bought the 260sq m house in 2002, it belonged to a sculptor who had turned the former car repair workshop into a modern space. “It had such wonderful light, and I loved the idea of living in what is like a glass box,” she says, pointing upwards to the glass atrium, three storeys above us, through which we can see plants waving in the wind on the roof terrace.

The space didn’t need much structural work. Etro kept the black marble floor, which suited her because she is allergic to dust and wool. The walls were already sleekly plastered and white. And there were plenty of small rooms which could be converted: in the basement to a nanny’s quarters and laundry rooms; on the ground floor to a bathroom, kitchen and walk-in wardrobe; on the first floor to a study-cum-child’s bedroom and second bathroom. “All I added were more glass walls and air-conditioning,” she says.

Inside the white, open-plan space, furnishings were kept simple to best show off the pieces that she and her brothers have collected on their travels. The sofa, for instance, is plain grey soft flannel, to accentuate the cushions, in Etro patchworks, Chinese embroidery and velvet. The low music cupboard (where she keeps vinyl LPs and 45s from her parents’ and her own childhood) is plain black, to bring out the vibrant hues of her collection of 20th-century cigarette cases. And the unadorned metal and black glass sideboard beautifully frames her global treasures: a gold-painted Russian icon from her maternal English grandmother, kitsch neon Indian collages covered in garish sari fabrics and sequins, a wire Eiffel Tower with toy car beneath it, a glass-fronted box holding the torn, over-loved red and white blanket she sucked as a baby.

“For me, a house is all about your life, your character, who you are,” she says. “So I find it very difficult to hide who I am – it just comes out in the things I buy.” Which is why there is plenty of fun and colour about. On the wall, amid antique, Greek, Japanese and pretty English plates, hangs a plain white one with a plaster-of-Paris fried egg stuck to it, and another bearing the faces of Grace Kelly and Prince Rainier. “It’s kitsch, I know, but they make me laugh,” she smiles, slightly embarrassed. Ditto the Cath Kidston cowboy fabric on Filippo’s bed, the Ingo Maurer heart-shaped red lamp on her bedside, the drawing of Alice In Wonderland, Frida Kahlo-style, in her bedroom, with a blank face and single black eyebrow.

Kahlo’s image appears frequently in the house. In the living room a 6ft-tall coloured photograph of Etro’s favourite artist, Yasumasa Morimura, dressed up as Kahlo, dominates the main wall. Above the sideboard hang black and white photographs of Kahlo. “I loved her sense of colour and her strength,” Etro says.

“I don’t like anything too fussy,” she adds, pointing out the raw cream rugs embellished with tribal patterns, the rough square coffee table covered in brown and black string, the elegant three-legged Patricia Urquiola stools and the Gae Aulenti rocking chair. “Rather I like things with a beautiful shape, or that make you think.”

One of the joys of visiting this home is the variety of things there are to see and the clever way in which they have been mixed. At the dining room table, for instance (square and lacquered in pink by Gallery Luisa delle Piane), every chair is different – as are the plates, glasses and cutlery with which she lays the table. “I cannot see why people have to have sets of everything,” she says. “Isn’t it more fun to change things around?”

Her favourite room is her walk-in wardrobe. Every glass-doored closet is lined, from floor to ceiling, with the sort of clothes and accessories most women can only dream of: row upon row of elegant shoes, from sparkly Jimmy Choos to flat Chinese pumps; piles of shirts, all neatly ironed; railings of trousers and jackets; an entire cupboard of fabulous eveningwear; and, of course, dozens of Etro treasures. “The funny thing is that by the time I have finished designing a collection, I am so sick of it I don’t want to wear it until about two years later,” she says. “And by then it’s out of fashion. So there are downsides to being a designer.”

www.etro.com

Times recommends

• Second homes: credit crunch casualty or money-spinner?
• How I built my own sliding house
• Top 10 incentives for house buyers