Coco's Caledonia: How Scotland left its mark on one of the world's most famous fashion houses

• Coco Chanel was credited with catching many salmon on her trips to the Duke of Westminster's estate in Sutherland

YOU don't need to be a dedicated follower of fashion to recognise classic Chanel. The tweed jacket, lined with silk, the padded leather handbag suspended on a gold chain, the ensemble completed with a pair of two-tone slingbacks. These garments, often modelled by their creator, have been worn by the most stylish and beautiful women of the 20th century, including Grace Kelly, Jackie Kennedy and Elizabeth Taylor. They create a style that is both unmistakable and yet utterly unique.

What has been unknown until recently, though, is that the inspiration for each element of this iconic style can be traced back to Scotland.

The connection has been revealed for the first time in a new book by writer Justine Picardie. Through painstaking archival research, Picardie discovered that Chanel spent three consecutive summers – for up to four months at a time – in Scotland with her then lover, the Duke of Westminster, in Sutherland.

These extended stays allowed Chanel to indulge her passion for the outdoors, and had a direct impact not only on the fabrics she later used in her designs, but also in the textures and motifs that are now seen as an intrinsic part of the style of Chanel.

"The two-tone shoes are the kind of shoes that the Duke of Westminster would've worn," says Picardie, "the tweeds are absolutely the Scottish tweeds, the softness of them washed over and over again before they're woven. The fluidity of the jacket seems to me to go directly back to those influences in Scotland in the 1920s."

So how did a woman synonymous with the glamour of Paris find herself in the wilds of Sutherland? Picardie discovered that Chanel travelled with the Duke of Westminster to his 100,000-acre estate in the late 1920s. There, in the fishing records still kept in the fishing lodge near Lochmore, appears Chanel's name, alongside the Duke's and his frequent guest, Winston Churchill.

"It's fascinating that it has been totally hidden," says Picardie, "not intentionally hidden, but that it was just sitting there in these fishing archives. It was astonishing really, turning those pages. We think of Chanel living around Paris and the French Riviera and, in fact, she was up in the Highlands. Not only the Highlands but one of the remotest parts of that region."

Chanel's interest in Scotland was not just a passing fad. The time that she spent near Lochmore and in Stack was mostly spent fishing for salmon and wild trout in the River Laxford. Winston Churchill wrote to his wife, Clemmie: "She (Chanel] fishes from morn to night, & in 2 months has killed 50 salmon." Chanel also, of course, discovered local cashmere and tweeds, fabrics which would become key elements in her designs.

The photographs Picardie unearthed show a woman truly in her element. Wearing her lover's tweed jacket and slacks – a habit that she'd developed with her previous lover, 'Boy' Capel – a woolly jumper and socks adding splashes of pattern, hiking boots looking both comfortable and sturdy, Chanel looks stylish, of course, but nothing like the image of the fashion icon that came to dominate late in her career. If by then she had become known for a kind of formality and a certain harshness, none of that exists in these early photographs.

"She just looks so free," says Picardie. "The happiness on her face is the complete opposite of what we think of when we imagine this very guarded, poised, intense icon which is how she became known in later life. The (photographs of Scotland] are the happiest pictures in the book.

"I've looked at so many photographs of Chanel in the course of writing the book and the ones taken in Scotland really do show her at her most unguarded and relaxed."

Picardie reveals a fascinating insight into the woman who created the Little Black Dress and who freed women from the constraint of corsets, stating with trademark didactic eloquence: "Elegance in a garment is the freedom of movement." But from where did this desire to be free come from?

Picardie spent time in the orphanage in the village of Aubazine where Chanel grew up; she worked on her book in the designer's Paris apartment above the famous boutique on Rue Cambon; and slept in the room across the street in the Ritz Hotel where Chanel slept from after the Second World War until her death in 1971. Each place informed Picardie's sense of the woman behind the name, and although Sutherland might have been the most surprising and revealing location that Picardie discovered, each place from Chanel's early life had an impact on her unique aesthetic sensibility.

Picardie spent time in the convent – still a closed order – in the small village of Aubazine in the Auvergne where Chanel spent the years from when she was 12 to 18. Having been born into grinding poverty in 1883, Gabrielle Chanel and her two sisters, Julia and Antoinette, were placed in the convent's orphanage after their mother died in 1895. There she found designs that could be traced in Chanel's later work. It wasn't only in the austere black-and-white habits of the nuns – Chanel was the first designer to put women not in mourning or service in black clothes -- but also in the patterns of the simple stained glass and mosaic floors. Chanel used her own history to inform her creations, those from Scotland and from every period of her life.

Another of the designer's lifelong habits was treating her own life story as a garment to be unpicked and remade to her own liking. How difficult did this make things?

"I found it challenging but also incredibly intriguing," says Picardie. "In a sense everyone rewrites history. The traditional biography says this is the truth and it doesn't acknowledge that in fact there may be several different truths and, of course, different people see things in different ways."

By using the archives of the House of Chanel, of course, but also those of the Duke of Westminster and Winston Churchill, Picardie has managed to create a truly three-dimensional portrait of an enormously complex woman.

"Chanel did say different things to different people," Picardie says. "I felt it would be dishonourable as well as dishonest not to include those different versions."

Tucked away in the remoteness of Sutherland, surrounded by the ancient mountains and the glens of heather and bracken, it seems that this is the place where the most unexpected and unexplored version of Chanel might be found.

"There must have been part of her that could relate to that very wild place," says Picardie. "The orphanage at Aubazine is a very remote place too. It feels different to the Highlands but there is a feeling of distance, it is almost unimaginably distant from her life in Paris.

Maybe there was something in her that responded to that wildness?"

It's clear that Picardie's book has been a labour of love. Spending time in the places where Chanel had lived played a vital part in her construction of the woman behind the name. Nowhere was this more true than in the Highlands.

"Standing by the River Laxford and also being inside the house at Lochmore which is now empty… I felt such a sense of the past and the present merging together," she says. "The landscape hasn't changed, the houses haven't changed, there are no layers of modernity which have been added. It's the same at the convent in Aubazine and in Chanel's private apartment in Paris. The veil between the past and the present somehow becomes very transluscent. It felt very real but also in a way magical."

Chanel was famous for her maxims and I wonder after nearly ten years of researching this most complex of women, if Picardie has a favourite?

"'Fashion is not simply a matter of clothes, fashion is in the air, borne upon the wind,'" she says immediately. "In that you get Chanel's ability to see how things come and go, in life as well as in fashion. It evokes the same lightness that you can see in those pictures of her in Scotland. When you stand in those hills in Sutherland you do have that sense of the permanence of the landscape and yet we come and go. It puts things in perspective."

• Coco Chanel: The Legend and the Life by Justine Picardie is published by HarperCollins, 25. Justine Picardie will be appearing at Lennoxlove Book Festival in Haddington on Sunday November 21 at 3:30pm. For tickets call 0844 357 7611 or go to www.lennoxlovebookfestival.com.