This interview appeared in Volume 12 of SUITCASE Magazine.

Stepping Stepping across the threshold of Katharine Hamnett's house in Hackney is to step into another world. "I'm trying to imitate Picasso's studio in Paris - you know, all covered in mirrors and trees," she says, standing in her dressing gown. Her Yorkiepoo Arthur accompanies us as we pass three studio assistants dressed in white T-shirts with WORLD PEACE NOW printed in black across the front. One of them brings a fresh pot of coffee to us as we sit down in Katharine's garden patio, which is wild and brimming with life.

It is easy to forget, as Katharine gently welcomes me into her home, that this is one of the fiercest women in fashion. The British designer is now 68 years old, a pioneer of ethical and environmental fashion and the inventor of the slogan T-shirt as we know it. She was awarded a CBE in June 2011 for services to fashion, and has been described as "the most copied designer in the world".

"It's much easier now, as people understand that sustainable clothing shouldn't look any different to normal fashion," she says of her work, before adding: "In the beginning it was a lot of people with huge hearts, but no fashion training."

Katharine began studying at Central Saint Martins at the age of 18. She launched her eponymous brand in 1979 and made her first slogan T-shirt - CHOOSE LIFE - in 1983. A year later, she turned up at Number 10 Downing Street wearing a T-shirt that read: 58% DON'T WANT PERSHING, and was photographed shaking hands with then-prime minister Margaret Thatcher. (The slogan referenced polls showing public opposition to the deployment of US Pershing missiles in the UK at the end of the Cold War.)

For some time in the Eighties, Katharine Hamnett could do no wrong. Her designs became cultural signposts for contemporary life and were copied all over the world (Frankie Says Relax, anyone?) "We were massively successful, selling in 40 countries and 700 of the best shops in the world," she recalls, saying: "The worse we behaved and the naughtier we were, the more everyone loved it." It wasn't until 1989 that 'bad behaviour' took on a new dimension of meaning for Katharine, when she researched the impact of the clothing and textiles industry. With an awareness of the damage inflicted upon humans and the environment by the widespread use of pesticides, she decided that things had to change.

"I've got a very murky past," says Katharine flatly, the way she says everything. She puts down her coffee cup and looks me in the eyes as she continues: "I invented stone washing, which sucks up rivers." Katharine goes on to explain that she pioneered distressed denim, stretch denim and lycra, all of which have damaging environmental effects. "I used to design fur coats before I had children. Then I realised it was really cruel and I stopped doing it. I think a lot of people say they get interested in the environment when they have children."

Not one to sit and patiently wait for tides to change, Katharine quickly cleaned up her practices. Her Autumn/Winter 1989 Clean Up Or Die collection used organic cotton and sustainable fabrics, and in 2005 she designed organic cotton T-shirts for Oxfam's Make Poverty History campaign. According to Katharine, the true price of cotton is paid in human suffering by the people at the bottom of the supply chain.

"Cotton accounts for 10 per cent of the world's agriculture. Switching to organic not only improves farmers' lives immeasurably, allowing them to feed and clothe their families, educate their children and afford healthcare, but its impact on the climate and environment is also massive." According to Pesticide Action Network UK, cotton is responsible for the release of 16 per cent of global insecticides, more than any other single crop.

She explains that the onus falls upon consumers to inform themselves and demand sustainable clothing. Shopping more consciously not only does justice to those further down the production line, but also has a positive effect on the buyer. Katharine explains: "T-shirts are okay for PR, but how many slogan T-shirts do you have in your wardrobe and how often do you wear them? Actual clothing, made responsibly, is a nice thing to put on in the morning. We've been doing organic cotton T-shirts, and people tell me they feel different when they wear them. It's nice wearing something with a clean conscience."

Referring to the Rana Plaza tragedy in Bangladesh, in which over 1,000 garment workers died when the building that housed their factory collapsed, she continues: "We're the ones who bought those T-shirts that were too cheap to believe. It's easy to think, "Oh it's the brands that should pay the compensation." The true price has been paid in human suffering and we should send that money ourselves. Send the £10, £20, £50 that was missing off the price of that T-shirt to the Rana Plaza compensation fund. We are responsible as well because we bought the clothes that were too cheap to be true."

Katharine speaks in long, multi-clause sentences, revising and editing ideas from the course of her career. She is so opinionated about such a range of topics that it can, at times, be hard to figure out where her focus lies. Our conversation moves from fracking to women's magazines to direct democracy (Katharine was going to start her own political party before the UK General Election based on the Swiss government, because "we're not living in a democracy; we're living in a two-party dictatorship".) "I've always been kind of scattergun about anything that bugs me," she admits. Does she thrive on being provocative? "No, no," she says, averting her eyes, leaning back slightly in her chair and reaching her hand up towards a vine dangling from one of her many overhanging plants. "I'm totally lazy. I want to be a gardener. I just want to do some flower arranging." Then as I stand to leave Katharine's own oasis, a wry smile flits across her face, and she leaves her answer hanging in the air.