When it comes to matters sartorial, it's usually the Duchess of Cambridge who creates a fashion furore, as every style watcher on the planet analyses every thread, every seam, every button of her carefully chosen ensembles. Yet, making a surprise call on Kensington poppy sellers in a mundane red coat a few days ago, she did little to excite newspaper editors and fashion commentators. Our future queen suddenly appeared rather dowdy in comparison with a number of high-profile women who are looking east for wardrobe inspiration as the Asian influence on fashion continues to grow.

Last week, the prime minister's wife took her cue from Indian style when she accompanied her husband on a visit to Shri Swaminarayan Mandir, the Hindu temple in north-west London, to celebrate Diwali. Discarding her signature pared-down, urban yummy-mummy style, Samantha Cameron wore a russet silk sari with an ornate jacquard-woven gold border design.

Draping seven yards of material around the female form may sound a challenge but it is second nature to millions of women who go about their daily lives in traditional Indian attire. For Mrs Cameron to model this textile version of origami on her fashion-conscious frame was a bold and brave decision for a political photo opp. Her sari was borrowed from a friend – who had clearly either been on hand to act as a dresser for the day, or had provided excellent tuition – and the 42-year-old carried the look with panache.

"The other ladies that met her were truly pleased to see the effort that she had made, and indeed many were left wondering how she managed to carry the sari so well," said Sejal Saglani at the Mandir, when I asked how the ensemble had gone down. "The fact that Mrs Cameron made such a huge effort to dress as per Hindu customs most definitely shows how much she values our culture, religion and traditions."

Yet I couldn't help feel that this was all a rather gauche form of fancy dress: another woman in the spotlight trying to make a statement by mimicking the complex cultural costume of her host. Mrs Cameron, usually confident in her own style identity and a worthy ambassador for the British Fashion Council, is wise to the nuances of dress, yet here she was, resorting to copycat style to "fit in". While her outfit may have been well received by the women who gathered in their own jewel-hued saris to meet their guests, the wisdom of her choice was questionable.

In the same week that Mrs Cameron visited Neasden, the Duchess of Cornwall began an official trip to India with Prince Charles, gracefully donning a number of permutations on the traditional shalwar kameez, to great effect.

The duchess and Mrs Cameron are, of course, the latest in a long line of women who have elected to mimic other cultures in their wardrobe, with mixed results. Diana, Princess of Wales, was an early advocate of the adoption of eastern costume, taking her cue from her close friend Jemima Goldsmith, who had more valid reasons to wear the shalwar kameez when she married Imran Khan, the former Pakistan cricket captain turned politician, and converted to Islam.

We've seen Elizabeth Hurley parading in glamorous silk saris during her marriage to the Indian businessman Arun Nayar. Others to have experimented – sometimes with dubious outcomes – include Theresa May, Cherie Booth, Naomi Campbell, Helen Mirren, Katie Derham and Tori Spelling.

The language of clothes is carefully coded as a result of thousands of years of social, cultural and religious lore, and the unspoken rituals that dictate what we choose to wear. As a race, we make instinctive judgments based on appearance and attire. It may make us uncomfortable that superficial impressions are so fundamental in forming opinion, but such impressions are deep in our subconscious.

In her book Understanding Fashion, the cultural historian Elizabeth Rouse explains: "Clothing is not a random or totally individual affair: it is a social activity. The overall pattern of our dress, be it grass skirts or tailored clothes, is a consequence of the society in which we live … we cannot interpret the clothing of other societies, we cannot understand their significance, if we have not learned the code," she says. "There are strict codes of dress for the wearing of traditional clothes. The type of fabric, the colours, the type of design or pattern on the fabric, the length of sleeves, the way a sash is tied, all act as signs and social meanings."

Alice Cicolini, former director of arts and culture for the British Council in New Delhi, now a jewellery designer based in London, describes her fashion faux pas on arriving in India, wearing a short sari. "Everything about your sari is a social signifier, and only members of the lowest caste would wear a short sari," she says. "All my colleagues were horrified, but that doesn't make me not want to wear it again, because I am not Indian and it is about my own expression and experimentation with influences.

"I love the fact that saris embrace all figures, and look amazing on everybody. There is something very democratic about that. I acquired lots during my four years in India, and really took pleasure in immersing myself in the aesthetic while I lived there, but actually they really don't feel very relevant back in London."

So, take traditional costume out of context and it feels awkward. Discussing the specific language of costume around the world, Rouse says: "Many Asian women retain the sari as a form of dress, despite its impracticality in British winters, because of its social significance within their culture as an expression of loyalty to that way of life."

And it is the significance of clothing in relation to a specific culture that makes me uncomfortable with the casual adoption of traditional attire for "an occasion". It feels too nonchalant, somehow, too lacking in respect for the rich heritage and language of such attire. Because the sari is so deeply ingrained in a certain ethnicity, it is not easily adopted by others.

Jessica Frazier, a fellow of the Oxford Centre for Hindu Studies and founder and managing editor of the Journal of Hindu Studies, stresses the importance of getting the detail correct when wearing a sari. "It is laden with unwritten language: the way you tie it, the length, the fabric, the way the pallu is draped over one's shoulder, the under blouse, the accessories, the posture," she says. "It is a very grand statement, and finessing that is crucial. The Hindu community is very good at letting other people into their space and [letting them] borrow their cultural goods, as long as it is done respectfully, but I have never worn one for work or even to a function hosted by Hindus. I prefer to wear an Indian scarf or some jewellery as a mark of respect."

It is this nod to cultural heritage, rather than slavish imitation, that tends to result in a more successful look. The Queen, probably the world's leading arbiter of social and sartorial protocol – thanks to decades of state visits and experience of dress codes – takes her cue from her hosts, appropriating a colour or a national emblem within a garment that itself sits within her own clothing comfort zone.

Michelle Obama nailed this dress-code problem perfectly in her own Diwali ensemble last week. The First Lady cleverly chose a silk shift dress by Mumbai-born, New York-based designer Naeem Khan, deftly combining a western silhouette with a skirt embellished in exotic silken embroidery that would not have looked out of place on a Rajasthani maharaja. She looked at ease and elegant, seamlessly blending two cultures in a way that was far removed from the clumsy costume-wearing of others.

I turned to Bandana Tewari, the fashion features director of Vogue India, for her thoughts on the matter. "If I wore a kimono today I wouldn't be as comfortable as a Japanese lady, because I don't have the cultural upbringing to look like a lady in it," she says. "Women who wear saris every day can do cartwheels in them, because it is second nature to them to move easily in them.

"I think it [the sari] is a more versatile garment than the rest of the world sees. When I travel outside India, the Indian women I see elsewhere are much more traditional in the way they wear them. Here, we have much more fun adapting our saris to a modern lifestyle, blending our own aesthetic with western influences. I wear a little black sari in Italian chiffon with a bikini blouse and Louboutin heels, in the same way that western women wear a little black dress."

So, across the globe, different cultures pay their respects to others most successfully when they seamlessly integrate their heritage to create a new aesthetic that sits comfortably with contemporary ways.