IT’S a dirty thing, being a sculptor, Nicole Farhi admits. "It's plaster, sand, cement. I quite enjoy that actually," she says, the perfume of her French accent scenting every word even though she's spent much of the last 30 years in London. "I enjoy being dirty after all those years being clean."

Now in her seventies, Farhi has, slightly messily evidently, reinvented herself. From the 1970s to 2012, she was a fashion designer, first for French Connection and then under her own name. And not just any fashion designer. Her clothes were worn by the likes of Emma Thompson, Cate Blanchett and Colin Firth. For a time, there in the 1990s she could even have claimed to be the unofficial designer in chief for New Labour given that both Tony and Cherie Blair would often kit themselves out in the Nicole Farhi label.

That was then. Her time in fashion came to an end some years ago, a victim of the downturn. Now she spends her days (weekends too) in her north London studio working with plaster and sand and cement.

The results of that work can be seen later this month when an exhibition, Writing Heads, opens at the Fine Art Society as part of the Edinburgh Art Festival. As the title suggests, it's a collection of busts of 20th-century novelists and playwrights, 25 in all, ranging from Francoise Sagan to Samuel Beckett.

"It began for my own pleasure," she says "and actually to give David, my husband, a present."

David in this case is the playwright David Hare.

"David wrote a play called The Judas Kiss which was about Oscar Wilde,” she continues. “It was revived three or four years ago with Rupert Everett playing Oscar. I decided to do a little mini portrait of Oscar Wilde to give David for his first night present. And he was so happy that when he did an adaptation of The Seagull at the National Theatre, I did a little Chekov. And then he did The Master Builder and so I did a little Ibsen portrait. And I had such pleasure doing those I decided to keep going."

Scotland looms large in the Farhi household this summer. As well as her exhibition, Hare has Peter Gynt, a freewheeling take on Henrik Ibsen’s Peer Gynt, opening as part of the Edinburgh International Festival. Both will be coming up to Edinburgh as a result.

And Scotland is also the homeland of Farhi's artistic mentor the late Eduardo Paolozzi, whom she first met when she was casting her very first bronze at the Royal College of Art.

"He came and looked at what I was doing. That piece, which was called Orgasm, was the beginning of our friendship. He invited me to his studio and little by little we became extremely good friends until he died.”

She speaks about him at length and with obvious fondness. "He was incredibly generous; he was bigger than life. He was interested in everything and everybody.

“He could lose the interest very quickly, too," she adds. "But to start with he was open to everything. He loved food, he loved sex, he loved women, he loved art, theatre. He loved the rubbish he could pick up in the street. I'd go to his studio and it was packed with not only his work but all the stuff that interested him."

Is your studio as messy, Nicole? "Mine is full of work so it's becoming smaller and smaller, but at the end of the day I tidy up and I tidy up again before I start."

Farhi's account of her own life is equally neat (although her sentence construction now and again is charmingly French). There are no ragged threads visible at any rate. And 2019 for Farhi would appear to be a happy round of work ("that studio calls me every day. I can't wait to get back there") and pleasure.

There's the odd shadow, to be fair. Brexit, for one. "I just find the whole thing totally ridiculous. We're becoming an insular country, an island again. I think it's going backwards, this country. It is very sad."

That aside, she loves her work and, when she wants a break from London, she still has a place in Paris.

"When I go to Paris I go back into my old life. I see my friends from when I was a student and we go out. I never cook in Paris. I never eat at home. I eat my breakfast at a cafe like I used to, a quick lunch in a cafe again and then a nice little restaurant in the evening with some friends. I go to museums. I see art shows. I go to the movies. It's really a holiday. I don't go to work in Paris."

This all sounds picture perfect, but inevitably her back story has the usual mix of light and shade.

The daughter of Sephardic Jews, Farhi grew up in Nice, where her dad ran a lighting business. Members of the family spoke the romance language Ladino, though Farhi grew up speaking French.

"I had a very colourful childhood,” Farhi suggests. “My family came from Turkey and although I am French – very French I think – I like the fact that the history of this family comes from all over the place; not just Turkey, but Egypt, Iran. They were a diaspora of Jews.

"My parents were from Turkey, but their parents were Spanish, so I loved that history of my family. The women all had accents and my father had a very strong accent, so I felt different and I liked the difference."

Farhi was born in 1946, however, and so the shadow of the war can't have been far away, surely? "Well, maybe the fact that a lot of our family went into hiding in the middle of France they did not so much want to talk about the war when I was growing up. They wanted to live in the best way possible. They enjoyed going to the countryside, they enjoyed the sea, they enjoyed life.

"We would go en famille every Sunday in a possession of cars going to this restaurant above Nice to a restaurant and there would be 20, 25 of us; the whole family. And I think that gave me a wonderful sense of security."

Still, she admits, she did ask questions. "One of my cousins had been in a concentration camp. He had the numbers tattooed on his wrist. So, maybe aged six or seven, I started asking him questions." She asked her parents, too. "But they didn't want to dwell on it. They didn't want to talk about it."

Farhi says she got on very well with her dad. Her relationship with her mum was a little more up and down. "She had a very strong character. So have I. I just couldn't wait to leave home and go to Paris."

And yet in the end it was her mum who helped her get away. "I realised she was on my side, whereas my father, who was all love for me, wanted to keep me at home. She was the one who helped me get out.

“We carried on all our lives to argue and love and argue again. She came to live with me in London in the last years of her life. She died a year ago at the age of 102."

That's something to aspire to, Nicole. "I know. I feel that, although I started this life as a sculptor late, if I think of my Mum, I still have quite a lot of years in front of me."

Farhi left for Paris in 1967 to attend art school, where she studied art and fashion, although like any student worth her salt, much of her time was spent in cafes and going to the movies.

"I was lucky to be able to do what I wanted and certainly felt totally free as a woman. That's when I discovered Simone de Beauvoir and, yeah, they were lovely years."

It helped that she had a facility for drawing and began to sell sketches from her fashion classes. "I drew easily and had loads of ideas and I earned some money. So, fashion gave me the freedom to be able to rent a studio, to go to restaurants.

"And, also, it was good fun to do fashion. It was the beginning of Pret a Porter. I think I was the second generation to understand that fashion should go into the street and you should stop thinking about haute couture. You could design nice clothes and not just go to a supermarket and buy horrible clothes. And I was good at it, so it took off very quickly."

Of course, she was also a child of the times. Come 1968 she was on the barricades in Paris, she says.

"When I met Stephen Marks [French Connection founder] later, he said 'you are a rebel without a cause.' Every cause was my cause. I was always fighting for something and certainly felt totally free and you could be then."

Marks was to become her business partner and eventually her husband. They had a daughter together, Candice. But the business lasted longer than the marriage.

After working for French Connection Marks and Farhi then launched a label in her name. It changed her attitude towards how she worked, she says.

"What it meant was that there would not be one thing carrying my name which would not make me proud. I became much tougher about my own work and I suppose I became a better designer. Whether it was good or bad I had to be responsible for my own name."

Her style was elegant, chic, unstuffy and loved by many. (Interestingly, her sculptures, by contrast, have an earthy, grungy physicality to them; Orgasm, for example, is an abstract piece that wouldn't look out of place on the set of the Alien movies).

Farhi was awarded an honorary CBE in 2007 and she talks of her life in fashion with evident pleasure. "It took me to places like India and China and Japan. It made me travel the world. I had a very charmed life." It gave her a second husband too. She met Hare at the start of the 1990s when she designed clothes for his play Murmuring Judges.

And yet even while she was being successful and dressing the rich and famous there was still a tiny niggle, she says. "I think I was 32, 33, and I thought, 'Well, it's all wonderful to make nice clothes but how can I express something else? If I'm angry or sad. You can't say that with your clothes. Or at least I was not able to do it. And so, I started sculpting and there I could let go of my emotions."

She still enjoyed creating clothes, but the last years of her label were, she admits, difficult. When French Connection got into financial troubles the Nicole Farhi label – itself making a loss – was sold off to a private equity company. It didn't go well for Farhi.

"With Stephen, I never considered him my boss. We were completely equal. We could talk. I could argue with him. We had a wonderful relationship.

"With the people who bought my company I didn't have that rapport and obviously no history and I got very disappointed terribly quickly. The first buyer sold my flagship shop in Bond Street immediately. Like, two weeks after he signed the contract. And then it was my homeware shop. He really was there for the assets.

"Then I saw a different world that I had never seen before because I was protected by Stephen. I didn't know what it was like out there. Obviously, the company had to be successful. But Stephen never made me think we were in it for the money. He made me think I was there to make lovely clothes that people would enjoy wearing and I would enjoy designing. So that's why the last two years were not great."

Was there a freedom in walking away then? "Oh yes, it was incredible. The day after my last show I was in the studio. I knew I had turned that page forever and I was opening a new world. A year and a half later I had my first solo show as a sculptor."

Life’s messiness can intrude in other ways. In April 2008 Farhi was held up at knifepoint, strangled, and robbed in London. The effect on her lasted longer than the bruises.

"It took me a year to feel that I can come back on my own without a problem," she admits. "I still don't like it very much. It's the only moment I can see that it has left a little scar. It might be for life. I am not as carefree as I used to be."

It makes me wonder, I say to her, if art, then, is a way of controlling the chaos of life? "That's true. I didn't think about it. But it's true that when you create you are in control of it totally. There's nobody else involved. You're on your own and you do what you want to do. Whether you succeed or not, it's your own decision."

Farhi, by any measure, can call herself a success. As you get older, Nicole, what does the word ambition mean to you now. "It's not a nice word, but I am ambitious. But I'm ambitious not to be better than other people, but to be better than myself all the time. I can't just live a life and be contented. I'm never contented. I want more.

"It sounds awful," she adds before she disappears to have her photograph taken. "I just want to keep going and discover new things about myself and new ways of expressing. The years we have on this Earth, I want to make the most of them."

And if that means getting her hands dirty now and again, she can live with that. She knows there are worse things.

Writing Heads opens at the Fine Art Society in Dundas Street, Edinburgh on July 25 and runs until August 25. David Hare's Peter Gynt runs at the Festival Theatre from August 1 to August 10.