Chanel after Coco in Coco Avant Chanel

The costumes for the upcoming film Coco Avant Chanel reflect some of the designer's most influential innovations. We look at their current catwalk incarnations.

The equestrian tweed - Ralph Lauren, autumn 2009.

With the long-awaited Coco Avant Chanel (Coco Before Chanel) opening in cinemas around the world over the next month, and Coco Chanel & Igor Stravinsky close behind, it's no surprise that interest in the creations of the great couturière has been reignited. The clothes that Audrey Tautou wears in the title role of Coco Avant Chanel were designed by the award-winning French costume designer Catherine Leterrier and approved by Karl Lagerfeld. They represent the early days of Chanel's life, when she was working as a milliner, rather than her interwar heyday.

The film may not cover Chanel's most productive years, but it reveals the background and the personalities that played formative parts in turning her from an orphan in the Auvergne into the most groundbreaking designer of the 20th century. The costumes have been researched meticulously from the fashions of the time and the Chanel archives, and there are unmistakable hints of the personal style that would make Gabrielle "Coco" Chanel so influential even a century later: the garments and workaday fabrics borrowed from menswear, sportswear and workwear, which chimed so perfectly with the privations of the First World War; the relaxed shapes following the natural contours of the body rather than squeezing it into corsets; the pared-back palette of black, white and neutrals. These elements were not only seen in her later collections but are now taken for granted as a crucial element in modern fashion's DNA.

Take the archetypal Chanel look, for example: the black jersey dresses and soft, unlined jackets, plainly cut and unadorned with frills or furbelows. These simple garments have found contemporary expression with designers from Raf Simons at Jil Sander to Alber Elbaz at Lanvin to Donna Karan. The LBD is a staple of women's wardrobes everywhere, an elegant, flattering testament to Chanel's lifelong fight against frippery and vulgarity.

Even those looks in the film that are not instantly identified as Chanel trademarks are easy to recreate. They were revolutionary at the time and are now considered classics to be reinvented year after year. The three costumes here represent in different ways Chanel's pioneering attitude to style: the comfortable equestrian tweed trousers, which she wore to facilitate horseback riding astride rather than the traditional sidesaddle; the men's suit and bowler hat, worn ahead of the Great War, when women adopted trousers as they worked in jobs left empty by the fighting men; and, of course, the classic Chanel jacket, a round-necked tweed number devoid of the structural constraints and interlinings that made tailoring so much less comfortable. And there is no shortage of reinterpretation available now because, to paraphrase Chanel herself, while fashion fades, only style remains.

Chanel may have been instrumental in women ditching corseted riding frocks in favour of comfortable horseback-riding trousers, but the tweedy country-sports look is one that has become synonymous with the American designer Ralph Lauren, and this season he doesn't disappoint. The tight little waistcoat and relaxed, loose, hard-wearing trousers have, as ever, a touch of Annie Hall about them (the Woody Allen film made Lauren famous), but it's more about the aristocratic polo set's effortless style than an urbanite's wardrobe. Other collections peddling variations on the theme this season include those from Chloé, Paul Smith Woman, DKNY, Rag & Bone and Sonia Rykiel - all brands known for turning relaxed fabrics and mannish shapes into super-feminine styles.

With those cropped trousers and the loose-fitting jacket, the boyfriend suit is a look that is completely on-trend this season and versions of the style have been seen on most catwalks, though more often teamed with soaring heels and black tights to add some vampish glamour. Jean Paul Gaultier, Paul Smith Woman, Marc Jacobs, Moschino... The list goes on. This is pretty much a signature look for Sonia Rykiel, who is a dab hand with a bowler hat, and for whom roomy low-slung trousers are a staple. But to avoid looking like an extra in a Charlie Chaplin film, rethink the elements of the style and wear them separately, as at Stella McCartney, where a men's tuxedo jacket works brilliantly over a voluminous white dress and super-tight fake-suede boots.

If Coco Chanel's design philosophy could be distilled into one garment it would be the house's immortal round-necked, unlined jacket. Whether cropped or hip-length, classic tweed or reworked in denim or leather, the shape is instantly recognisable and endlessly reinterpreted by other designers. Silk is quilted directly onto the outer layer, making it feather-light and as comfortable as a cardigan. The sleeves are high-cut and narrow, for a slender silhouette. A fine chain hangs beneath the silk lining, providing enough weight for the hem to hang correctly. And while the shape has appeared on many catwalks for autumn, it is at Chanel itself, which redesigns the iconic garment every season, that the original and best will be found - albeit with a punky makeover.