Colour crusader: How Tricia Guild become an interiors icon

How can people get over their fear of colour and pattern?" That, says Tricia Guild, is the single question she is most often asked.

And it is perhaps her enthusiasm for answering it, again and again, year after year, that has helped to make her company, Designers Guild – which started life as a small shop selling Indian-inspired block-printed fabrics in a, then, less salubrious stretch of London's King's Road – such an enduring success.

This year, Guild celebrates her 40th in the business, during which time she has expanded from simply designing and selling fabrics into wall coverings, homewares, furniture, paint colours, children's ranges and design services. She's built a global presence, written 15 books, been commissioned – more than once – by the Royal Family, garnered a long list of awards, including one for lifetime achievement, and been made an OBE for her services to interior design.

"Tricia Guild?" says a stylish figure in the interiors world. "She's the only person I know of who could design a bright orange sofa without it looking ridiculous. She's almost outside fashion and trends – she's her own trend." Walk into one of the Designers Guild shops or showrooms (there are now three in London, including a Selfridges concession, and two in Paris and Munich, as well as those attached to distributors all over the world), flick through any of those books, or browse the website – and the impact of that outsider trend is instant.

Guild is renowned for her striking use of colour and, yes, often it is orange – though it would never be just orange, or any other single shade, texture or pattern. Among this season's collections, for example, one range features a rich orange amid a palette of strong yellow and magenta velvets; bold grey/green/yellow/pink linen florals; lime, purple and pink lampshades; chenille swirls, black and white silk stripes; pink/grey/white checks and clean whites – and all against a backdrop that mixes mid-century modern with sleek contemporary and antique. Elsewhere, sumptuous ceruleans are combined with vivid purples and cool greens, and punctuated with flashes of acid yellow, fuchsia, huge digitally printed flowers and giant stripes.

It could be a headache-inducing horror. In Guild's hands, however, such combinations are mind-bogglingly inspired, inspiring and, quite simply, they look fantastic. Her confidence – and her eye – is extraordinary.

"Hopefully I don't follow trends, no," she says, sipping a coffee in the basement of her landmark Chelsea shop, the very same one she opened aged 22 in 1970 – but vastly expanded. "And hopefully I create trends – but that's not for me to say." She continues: "I think there has been a British reticence about being garish, which I quite understand. Hopefully this isn't garish" – she gestures around the shop – "it's strong and invigorating." She uses words like this a lot: her designs are "vivacious" and "dynamic", and since a life-changing, technicolor visit to India in her youth (it is what prompted her to open the shop), she has wanted to "show people how lovely it can be to live with colour". It is, she believes, "good for the soul".

The garishness of all of this, she continues, is partly avoided because it is carefully tempered. "A third of our fabrics are neutral – did you know that? And in every collection there's black and white. It gives harmony to colour. It's about finding balance."

What's interesting is that although Guild's style is instantly recognisable, it is also vastly versatile – as illustrated in her latest book, which showcases 14 of her interior design projects in houses that could not be more different. There's a City penthouse with a muted pink, grey and monochrome palette, a lakeside pavilion with greens, yellows and pinks linked by an oversized graphic print repeated around the house, and a stone farmhouse that's a patchwork of country florals and yet looks sharp and modern. "I wanted to show how flexible what I'm doing is, and how you can use it in large or small spaces, modern or old..."

Where does she start when coming up with her ideas? To illustrate, she describes perhaps the most challenging of the book's projects, a Norman manor house of flagstone floors, dark wood panelling and stone arches. "It is the ultimate proof that the age and appearance of a building does not have to dictate the approach to its interior," she says. "Not an easy space to make contemporary – but, as with any space, you look at its assets and try to work around the areas not compatible with the lifestyle to be lived there." Which, in this case, was one of a young family. The house must have felt the opposite of youthful when she began. "It was very heavy," she says, "very traditional. So my idea was to make it feel very alive and 'of the moment'." So it was out with the heritage look, in with contemporary sofas, a slightly retro feel, and masses of bright colours." The result laughs in the face of the idea that it is pale colours that lighten dark spaces, or that sensitivity to period requires rigidity.

How did she reconcile such a design ethic with the deeply traditional Royals, for whom she is now working on her fourth commissioned collection? "I was very touched to be asked," she says, "because in a way what we do is quite innovative so it was an interesting idea. It isn't about making it contemporary in the way that our fabrics are contemporary," she says. "It's respecting the traditional qualities and inspirations we found there. And yet making it right for the moment." It was, she concedes, challenging. And nerve-racking? "Yes – very. I hear the Queen sees everything, so it was quite daunting – but the remit's quite wide." She chuckles: "As long as it's liked!"

And with Guild, it seems, there's something for every taste to like.

'A Certain Style' by Tricia Guild is published by Quadrille (£40). To order a copy for the special price of £36 (free P&P), call Independent Books Direct on 08430 600 030, or visit independentbooksdirect.co.uk.