Nina Campbell's Chelsea home is a showcase for her very British brand of comfortable luxury

‘John was a very good teacher because he made you look at things. He didn't treat you as if you were an idiot and he was the brilliant one. We would be in a room and he would say, “Now, let's play ladies. Let's think about what the room wants.” Then he would pick out a colour from a tapestry and say, "We're going to call it Tapestry Green, we're going to paint everything in it, and it's going to look much better.” Which of course it always did, because he was a complete genius.’

In 1970 she opened a shop on the Pimlico Road with Mark Birley after helping him to decorate his private members club Annabel’s, one of the UK's first nightclubs which was the beating heart of London's cultural scene. A place where the aristocratic old guard and the creative, bohemian new guard mixed in rooms covered in wallpaper created from old documents Nina had pulled from the back of John Fowler’s cupboards.

Then there were the Eighties, when the curtain swags grew at the same rate as the shoulder pads. During this period she was covering Ringo Star’s house in chintz, and rummaging in the cellar of Buckingham Palace for pieces for Prince Andrew and Sarah Ferguson’s marital home. The success of her decorating business led her to expand into products and fabrics. You might not have been able to afford to have Nina decorate your house, but you could visit her shop on Walton Street and fill your home with her edit of china and linen.

In her 1997 Desert Island Discs interview Sue Lawley asked why she thought her company was so successful; ‘Six million pounds of wallpaper and fabric sold a year, most of it in America. Why do you think the Amercians are so attracted to your style?’ She was distilling a cozy, insouciant upper-class ‘Englishness’, and making it accessible to everyone. She was an influencer before influencers were a thing.

Nina grew up in Belgravia to a Scottish father and Austrian mother (‘I suggested to my mother when she was getting old that she might be better off coming to live near me in Chelsea. She said, ‘Darling, I'm already a refugee from Vienna. Must I become one from Belgravia too?”). A mother of three, she has been married and divorced twice, and is quoted as saying, ‘Husbands can come and go, but whatever you do girls, hang on to your curtain maker.’

She ‘really minds’ about the details, and nowhere is this more apparent than in her Chelsea house, where she has lived for the last fifteen years. It is an unusual space. A former artist’s studio which was formerly part of the bigger property next door. From the street it is virtually invisible; a gate in a brick wall, with none of the usual signifiers that someone’s home lies behind. It is a surprise when the door opens directly on to a book-lined entrance painted in ombre turquoise, separated from a long low living room by a fabric covered screen. ‘The colour comes from one of (the ceramicist) Kate Malone’s pots, which I collect. I did the flat glass ceiling to give the illusion of height. And then obviously the drinks as you come in, because that's important.’

When she bought the house it was ‘a horrid little des res’, and she had the whole interior gutted and rebuilt to suit her specifications. As a response to having to work within the restrictive parameters of planning regulations she has employed her full arsenal of visual trickery to give the illusion of space and light. ‘I wanted to create the feeling of a hall without chopping up the rather limited space. So I used this screen which has fabric on one side, and mirror on the other to bring the garden to the back of the living room. Then I had these bookcases created with mirrored slips, which is an old Elsie De Wolfe trick.’

In the sitting room, where regulations meant that they couldn’t make the ceiling any higher, she simply, ‘got rid of all the cornice and lacquered it. I was amazed by the result. I think it’s one of the best things I’ve done here.’ The gold and mirror fireplace is also folly. Another element of the house – like the ombre paint, or the 18th-century chair from Jamb covered in lime green horsehair – which in theory really shouldn’t work, and yet somehow does.

‘Oh, it’s a bit Alice in Wonderland. Because of the bores in the planning office we couldn’t make a working fireplace, so I filled the grate with crystal logs. The whole thing is insane. You've got logs which won’t burn, and mirrors everywhere, and this gold chimney breast that I dragged back from Atlantic Avenue in the USA. I love the whole nonsense of it. ’

But the ‘whole nonsense’ is countered by a pretty serious collection of art and ceramics. To the right of the fireplace, above the Kate Malone pots that inspired the colour of the hall, are paintings by her friend Sunita Kumar. On the fireplace are delicate ceramic flowers by Tommy Mitchell. ‘Pretty much everything I've got in here, if it’s new, is by someone who I know. It’s like I’m surrounded by friends.’

In the dining room, which is separated from the living room by an etched glass screen which can be pulled fully across for a ‘grand reveal of the dining table when I throw dinner parties’, is a huge mirrored cupboard made for her by her late-friend William Yeoward, which houses her enviable collection of tableware, glasses and linens.

The basement functions as a self contained flat, where friends and grandchildren can stay ‘in what people say is the most comfortable bedroom in London’. And upstairs in her bedroom, the fabric covered walls in a large floral print of her own design, echo the panorama of the upper branches of a magnolia tree. There are no cupboards in the room, and her dressing room is concealed behind a jib door hung with pictures. The adjoining bathroom is pure Hollywood. All baby pink walls and mirror. ‘As long as a room has a thread of some sort, even if it’s only in your own mind, that’s what makes it come together.’

She has been here longer than she has ever lived anywhere. Her homes throughout her life have been showcases for her design work, which she moved on from once they were finished. But it is also a house that in true Nina Campbell style, is totally tailored to the way that she wants to live now. ‘With houses, you know, it's rather like you climb up this mountain and then you climb down the other side. They get bigger and bigger as your children grown, then smaller again as they leave you. In this house I’ve even decided what I’ll do when I get to the point that I can't go up the stairs. It's all sorted,’ she laughs, ‘I’m going out of here in a box!’

At 78, Nina is still working full time on substantial interior design projects all over the world, and there is no sign that she is going to slow down any time soon. ‘There’s a feeling that perhaps I should be hanging up my clogs, but I don't think I'm going to really.’