Danielle Vanier is a fashion blogger. A recent post sees her in a keyhole-front leather-look jumpsuit teamed with red lipstick and matching ankle boots; on her Instagram feed she is captured in modern faux-candid selfie style, gazing out of a window in black lingerie. Vanier is 30 years old, beautiful, an ambassador for Nike, and a digital influencer with 100,000 followers.

She is also – to use her preferred descriptor – fat. The aforementioned lingerie selfie is captioned “Three Cheers For Back Fat”. “I have always felt that I could have belly rolls, I could have chubby legs, and I could still look great,” she says. Vanier is a consultant to Curve, a new Marks & Spencer range available in sizes 18-32, the first pieces from which go on sale today. That M&S, which is already the biggest retailer in the UK plus-size market with womenswear available up to size 28, has created a separate plus-size collection is a reflection of how plus-size women are demanding the industry serve their needs with the same degree of attention to detail as women shopping for a size 10.

Take sleeves. One £59 faux-leather jacket from the Curve collection has been a hit in pre-launch research, partly due to hidden stretch jersey inserts that make comfortable but shapely sleeves. “Arm circumference is one of those little details that make a difference in plus fashion,” says British plus-size blogger Lottie L’Amour. “We want clothes that accommodate our curves, and flatter our curves.” (Vanier, who is “obsessed” with the jacket, loves “not being sausaged into a sleeve.”)

Curve represents a shift in the emotional tone of plus-size fashion. “When I walk into a shop, I want to feel like the brand are proud of me. I want to feel that they want me in their store, they want me to look great in their clothes,” says Vanier. The size 20 mannequins on which Curve will be displayed in store had to be specially commissioned, as mannequins are only produced in size 6-8 as a “regular” size and a size 12 as a “plus” size. They may be a signpost of how stores will look in the future, as body size diversifies. Currently, the bestselling sizes at M&S are 14 and 16, with sizes 12 and 18 coming next, but the trend is for a broadening spread of sizes: as well as increased demand for the largest sizes, the store is seeing strong sales of size 6, particularly in its Autograph range.

“Body positivity” is a buzz phrase in plus fashion. L’Amour (example post: “Swimsuit or Bikini? Being body positive at the beach”) believes that the “curve” label is catching on because it reflects a more upbeat self-perception. “I don’t really mind what the clothes are called, as long as I can find them,” she says, “but some women don’t like being called ‘plus’. Curve sounds more flattering.” Pre-launch research at M&S pointed to Curve as the best name for the new range because “there is no fear of the term ‘curve’ – it has positive connotations”, says the store’s head buyer, Jo Hales. “I myself use the word ‘fat’ because I don’t see it as negative,” says Vanier, who trained as a textile designer.

Facebook Twitter Pinterest Plus-size model Ashley Graham, an activist for body positivity. Photograph: Angela Weiss/AFP/Getty Images

Retail is taking its time to catch up with the positive attitude of Vanier and L’Amour. “Sometimes I ask for a plus-size dress to wear in a shoot, and the biggest press sample is a size 16,” says Vanier with an eye-roll. She is frustrated, also, by the unambitious aesthetic of much plus-size fashion. “One of my favourite pieces in Curve is a sleeveless khaki trenchcoat, which I am obsessed with – you can layer it over jeans and a white T-shirt and it looks really modern. We need more of that sort of fashion.”

The attention being newly lavished on the plus-sized shopper is motivated by a clear business opportunity. While the average British woman is a size 16, only 20% of money spent on womenswear is spent on plus-size fashion. The industry is banking on the notion that plus-size women will spend more money on clothes if the offer becomes more appealing. The success of 11 Honore, which translates the Net-a-Porter model into plus-size with an edit of catwalk fashion in sizes 14-24, has revealed an appetite for luxury fashion, while brands such as Elvi (typical piece: black and polka-dot lace maxi skirt, in sizes 14- 26) and Premme (home of Vanier’s keyhole jumpsuit) have brought fashion-forward attitude to the plus-size market. Curve will face strong competition on the British high street from Asos Curve and River Island Plus, which have established themselves as go-to brands for plus-size shoppers with an appetite for catwalk and streetstyle trends.

Ashley Graham, who recently became the first plus-sized name to feature on Forbes’ list of highest-paid models, has evolved into an activist for body positivity. Recently, she has publicly called out Victoria’s Secret for not including any bigger models on their catwalk, and praised Italian Vogue for not retouching photos of her. The arrival of Curve at Britain’s most seminal high-street giant is a marker of how this confidence has trickled down to a high-street shopper who is no longer content to rifle through the back of the rack for a scaled-up version of clothes that the design studio conceived in a size 10.

Facebook Twitter Pinterest Danielle Vanier models her favourite item from the Curve collection, a sleeveless Khaki trenchcoat.

“What the plus-size customer is asking for now, as she becomes more discerning, is a range specifically for her,” says Hales. “This range is designed on a size 24 block, instead of a size 12 block, and sized up and down from there.” This has a tangible impact on design. A floral print, for instance, might look better scaled up so that it is in proportion with the expanse of fabric. “To get the perfect plus-sized jean, we have made it higher on the rise. With shirts, we have adjusted the relative size of the front pockets.” Non-cling fabrics have been used in pursuit of “a flattering silhouette, rather than a tent,” says Hales.

Acknowledgement that plus-size women want a full range of styling and layering options is still a work in progress. There are still lingering assumptions about who this woman is: that she wants an under-the-radar wardrobe, instead of wanting fashion. That she doesn’t like her body and doesn’t want to spend money on it. That she doesn’t work out. A stale industry squeamishness about plus-size translates into an undercooked, underseasoned final product. “Before, we were told to hide away, wear a sack, not wear a spectacle of ourselves,” says Vanier. “But now we go shopping with our friends, and we want equality.”

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