People used to go to fashion shows to see the clothes; now they go to be seen wearing them. The practice of documenting “street style” evolved in the 1980s, when style magazines such as i-D began chronicling people out and about. Today though, the stars of the scene don’t pound pavements hoping to be snapped on the street; they exit chauffeur-driven cars to totter the five or six metres to the fashion show venues, often posing on their phone or chatting with a pal in a matching outfit. Neither do they wear thrift any more: these street stars are seen in the latest designer clothes, sometimes just hours after their catwalk debut. It’s good news for the labels; it’s even better news for those canny enough to monetise their penchant for clashing print or double denim.

Conservatives within the fashion world may dismiss street style as part of the growing “circus” around the shows, but its leaders can translate an image into big rewards; from ambassador deals with brands and paid-for posts on social media to own clothing ranges and brand collaborations. The rise in street style has even sparked a wider trend in “real people”-led advertising. J Crew kicked things off in 2012 with a campaign starring Caroline Issa (chief executive and fashion director of Tank magazine), stylist Julia Sarr-Jamois and French journalist Virginie Mouzat. Last year, “Tod’s Band” campaign featured 15 personalities and fashion show regulars including Langley Fox Hemingway, Mae Lapres and Julia Restoin Roitfeld, while Chloé is currently popularising its bags and accessories on social media with the hashtag #ChloeGirls. Peacocking has never been so profitable.

It’s not only the street stars who are cashing in. Many of the photographers shooting the styles have turned their images into a viable business, among them Tommy Ton (who has shot for Condé Nast and his own site, tommyton.com), Scott Schuman of The Sartorialist blog turned book, Vogue contributing editor Phil Oh (aka Street Peeper) and Adam Katz Sinding of Le 21ème.

Katz Sinding has been shooting since 2007, but has only been capturing fashion week attendees since 2011. Now it’s a huge part of his work — he’s funded to travel by a range of clients, “from e-commerce companies, to publications, to the brands themselves”, and has a syndication deal with Trunk Archive for resale of his images. He’s watched the scene change enormously. “It’s been a very fast (de)evolution,” he jokes. “Back then, the people we shot were exponentially more authentic. There was not the push from brands that we now see. It was rare to see full runway looks walking down the street.”

Blogger Leandra Medine — aka Man Repeller — is a regular in Katz Sinding’s shots. Her idiosyncratic style makes her a photographer’s dream — the name of her blog is a nod to her kooky taste: clothes that stylish women adore but men find sexually repellent. She’s also noticed the commodification of the scene. “When I started five years ago, street style felt more like an indie art,” says the writer, who has worked with Saks Fifth Avenue, shoe brand Superga, Michael Kors and Maje on brand collaborations. “It’s become a sort of native advert in many ways — living, breathing sponsorships that look a lot like personal style but are actually motivated by something other than self-expression.”

Today, almost every label will spend time and money “placing” product. Gifting has long been a way of showcasing goods but, more recently, these gestures of goodwill have become more formalised arrangements. Increasing numbers of key influencers and “tastemakers” now take fees or enter contractual relationships to promote brands on blogs and social media. It’s a change that has been driven both by brand promotion and the thirst for imagery created by the enormous growth in editorialising in ecommerce sites.

“The essence of street style itself has changed,” says Yasmin Sewell, fashion director of Condé Nast’s new ecommerce site style.com (which will launch this year) and a much-photographed presence at the shows. “In its early days, the focus was very much on a person’s unique self-expression. There was no such thing as Instagram to determine a person’s ‘value’. Now it’s one of a brand’s most powerful marketing tools.”

The “product for post” concept — a freebie in exchange for a post on social media, or a shout-out at the shows — has grown in tandem with the street-style movement. “Only a tiny handful of brands can afford to put a full-page ad in a magazine,” Sewell continues. “But almost any brand can afford to gift a blogger or editor in the hope their product is worn and seen and will create demand. There’s so much strategy involved — the right placement on the right person, snapped by the right photographers and featured on the right websites can mean so much for a brand’s exposure and ‘covetability’.”

This transactional aspect of image-making has made Katz Sinding wary of describing himself as a “street-style” photographer. “I’m trying to capture something beyond the superficial commercial aspect,” says Katz Sinding, who shoots the looks outside the shows for W magazine and lists Emmanuelle Alt, editor-in-chief of French Vogue, Isabelle Kountoure, Wallpaper*’s fashion director, and models such as Hanne Gaby Odiele among his favourite subjects. “‘Street style’ to me, now, is showing trends and ‘important’ people dressed in ‘important’ brands — it’s a bit boring.”

The “important” people he speaks of aren’t celebrities but the once-anonymous fashion writers or stylists. Street-style fever has given birth to the strange notion of the “influencer” — someone who’s not traditionally famous, but can fit into high fashion and has upwards of 50,000 Instagram followers. For brands, images of these people can become vital advertising leverage, the importance of which will last far beyond fashion week.

Arguably, today’s influencers don’t need to be photographed: they must simply document themselves, obsessively. To Susie Lau, author of the fashion blog Style Bubble, this growth was inevitable. One of the most respected — and familiar — faces on the scene, admired for her support of young labels, her success has inspired thousands of copycats. “It doesn’t surprise me in the least,” she explains. “It’s only exploded because Instagram has become such a huge platform. But it was ever thus. There will always be girls who wear clothes really well.”

Blogger Pandora Sykes is great at getting dressed. She juggles her digital work and Instagram feed with a job at Sunday Times Style magazine. She says: “I’ve been very resistant to being a paid body — who wants to be a fashion sandwich-board? Someone being paid to wear something at the shows is just an example of how you can leverage your image and your personal brand. Bribery is rife. People think if they send something that that is some form of payment for a post. I’ve been sent umbrellas before and got a follow-up email saying it would be great if we could have a ‘cheeky little Instagram post’.”

Sasha Wilkins of Liberty London Girl, sums it up when she says, “Once you hit half a million followers on Instagram you can start writing your own cheques — ￡10,000 for a post with you wearing something.”

But are viewers or readers aware of these payments when browsing street-style blogs or Instagram? “Do the semantics really matter to who’s looking at them?” asks Lau, who has worked with the likes of Coach and Yoox and on sponsored blog projects and social media posts featuring products. For her, “it’s no different to flicking through advertising in a magazine. They’re looking at it for a fleeting second and they’ve given it a fleeting amount of attention.”

For Lau, “This is a new form of advertising and it is one that works because the images feel personal — those girls have built up a cult of personality. Though people may become numb to that — in the way we’re numb to traditional advertising today.”

That numbness is yet to kick in. For the moment, images of stylish women — and increasingly men — out and about shift product. “It’s the idea of real-life usability of the garments that draws people to our images versus catwalk looks. Seeing it in daily use really speaks to people,” argues Katz Sinding.

This idea of “real life” is the strange irony of the whole movement — it’s central to its success, but disappearing because of it. “I frequently turn down big money jobs because I’m not going to look good in a brand’s stuff and I won’t feel good in it — that wouldn’t do anyone any favours,” says Sykes. “I think brands can be quite naive about that. They should be striving for authentic relationships, not just people who have the most followers.”

Medine agrees. “My style is such an integral part of what I do professionally, I can’t really afford to risk the authenticity factor there,” she says. “The reason street style resonates and has become a phenomenon has everything to do with women seeing themselves in other women. The moment that jolt of authenticity is compromised and the trust between the voyeur and the wearer begins to break, the game is over.”