Neelam Gill claims that she was never taught how to pose or stand or pout or angle herself just so, cheekbones dipped and lips drawn slightly apart, for hours and hours in front of the camera. Being professionally beautiful doesn’t ever sound like it could be that difficult a job – 99% of it is surely just genetic lottery – but watching her up close in the studio, positioning and repositioning herself, is exhausting. “I would never complain about what I do,” she says later. “You fly to all these different places, you get off the plane and have to be ready to shoot and look amazing, then you fly back out somewhere else and do it again. I spend a lot of time lonely in hotel rooms and airports, I don’t go out, I can count the friends I have on one hand… But I’m always going to be grateful.”

It’s easy to suspect that Gill’s gratitude is tacked on for my benefit, but it turns out the model has plenty of reason to mean it. At 21, she is consistently written up as “the first British Indian model to…” The first to become a muse to a major fashion house with Burberry. The first to become the face of high-street teen emporium Abercrombie & Fitch. The first ever to appear in British Vogue. The working-class girl from Coventry with a Black Country accent and Giacometti silhouette has broken the mould in an industry perennially called out for being snobby and racist.

I didn’t make the first casting, because I couldn’t afford the train to London

Gill was 14, and spending her Saturdays tottering around the Birmingham Bullring in her best going-out clothes (bandage dress, skinny heels), when she was scouted by a modelling agency. It wasn’t until she was 18 and had got four A*s at A-level that her mum let her give modelling a go. She was signed up by Models 1, once home to the original supers: Twiggy, Yasmin Le Bon, Kate Moss, Naomi Campbell and Linda Evangelista. One of her very first jobs was being sent to meet Burberry, in 2014.

“I didn’t make the first [casting], because I was working in Hollister and I couldn’t afford the train down to London – it was like £70!” she says. “Models 1 were really angry at me and were, like, ‘That was such a big opportunity.’ But Burberry called again the next week, so I got the money together and went down for the day.” Gill says she was clueless, and turned up looking out of place among a sea of chic, understated, designer-clad pros, fresh from shows in Milan and Paris, practising their walks outside the office.

“It was like something out of Ugly Betty; I was just sat there with my long hair past my ass, hot pink nails, this diamanté top with huge platform boots and hotpants.” She was handed wipes to take off her makeup. “I’d never walked before, I’d never done any editorials or photoshoots, so when Christopher [Bailey, chief creative and chief executive officer of Burberry] looked in my book, there were no pictures, just Polaroids. I was, like, ‘Yeah, don’t worry I’ve got a few shoots coming up.’ I had no idea of the magnitude of what was happening.”

Bailey loved her and said he wanted her for the next catwalk show. Gill asked how the timings would work because, “you know, I’m gonna go to uni and stuff”; she was planning to study psychology. The Burberry campaign, titled English Rose and shot by Mario Testino, was her first ever job. Her degree plans are now on pause.

Dress, kenzo.com. Boots, marquesalmeida.com. Photograph: Gustavo Papaleo/The Guardian

“Christopher really believed in me,” she says, “we really hit it off. He’s from Halifax and he took a chance on this girl from Coventry.” Bailey told Gill she was the future of British beauty and to embrace her natural, Indian features; Gill’s dark skin, thick brows, the delicate tilt of her cheekbones and exaggerated lips might seem too much, too obvious, were it not for those eyes: huge but vulnerable.

Growing up, she says, there was no one famous or in fashion that looked like her. It took time, especially during her awkward teenage years, to be assured that “there isn’t one kind of beauty”. She’s hugely proud to be changing that, so that girls like her two sisters (Jasmine, 16, and Millan, three) won’t feel as unimportant and unpretty as she did. “But why did it take so long?” she asks. “I go to castings now and there might be one other Asian girl – agencies started scouting them after I started getting booked. That’s amazing. It’s an ongoing process, and it won’t change overnight, but sometimes… just what the fuck?!” We eye-roll at the same time; the fashion industry’s approach to diversity has barely changed in decades – last year’s runway report found that just 25% of catwalk models were not white; eight of the 10 most booked models were white.

Gill’s voice is soft, she’s gracefully mild-mannered and mellow in a way that doesn’t always correlate with how outspoken she is. As much as she prays – every night, she says – for stability and security, she hasn’t kept quiet on fashion’s failings. “I’ve got a thick skin,” she shrugs. “It’s easy to be, like, ‘This issue about diversity in fashion doesn’t matter because it doesn’t affect me.’ But people don’t understand how hurtful it is to be discriminated against.”

Gill has endured breathtaking racist abuse online since she entered the public eye in 2013, first as a model with opinions, later because it was rumoured in 2015 that she was seeing Zayn Malik. The subject of her alleged fling with Malik is swiftly avoided. She will say that she is close to producer Naughty Boy and rappers Krept and Konan, a unit of friends that the former One Directioner was part of before public fallings-out, meeting model girlfriend Gigi Hadid and moving to LA.

Gill says she never had a ton of friends back in school – “I’m not the one with the WhatsApp group of girlfriends that does everything together, I never had that” – and that even the ones she did have stopped being as close. Does her job make her feel like an alien? “It’s people from home who make me feel like an alien. I think they must think I live on a different planet and that I don’t see them posting bitchy things about me or talking about me, but I do. They’re not as happy for you as they first were. I get down. But it’s always going to be worth it compared with before.”

Dress, kenzo.com. Photograph: Gustavo Papaleo/The Guardian

Her parents, both from traditional Indian families, were born in the UK and had an arranged marriage. They struggled as a couple, working in her paternal grandparents’ corner shop and living in the flat above until they could afford to move to their own house. “It was the rough part of Coventry. There were rats and mould, and I have memories of my mum just being on her knees and scrubbing.” They had a messy divorce when Gill was seven; after the split, her father remarried without Gill meeting her stepmum, and later she discovered by chance that they were having a child together. She tells me in long, raw detail about the rows and hurt. “I thought I would never get over that pain. I remember just being heartbroken, I was numb for years and years. I always thought if I could get through that, then I could deal with anything.”

Gill cut off contact with her biological dad; her mum remarried when she was 13 and she later took her stepfather’s surname. “I don’t hold any animosity towards my dad, his wife or his kids. I’ve never met them, but I don’t really feel the need to. I feel a lot of guilt for what I put my mum through.” Gill says she became difficult and cold as a child. “I was really hard on my mum at a time when she really needed me. I wasn’t there for her. I do what I can to be better to her now.”

It was around 2015, just over a year after she started modelling, that deep anxiety kicked in. “I had a huge breakdown – I just felt so disconnected from everything. I’d lost so many friends, I’d moved to so many different apartments, I kind of went a bit distant from my family. They weren’t 100% happy with me because work stuff was crazy and they felt like they were losing me. I was getting all these big jobs, I didn’t think it was going to last and, you know, that was my main issue: I never ever said no. Even if I was exhausted or ill.”

Depression is still something I suffer with, but it’s something you learn how to cope with and you get help

Gill started waking up in the middle of the night in cold sweats, paralysed and rigid. Then the nausea and puking would start. “I would throw up non-stop and it was insanely painful. My throat would be red raw. The first time it happened, I thought I was dreaming.” It went on for months at night, until one day she vomited on a shoot and was sent home to her family for weeks to recuperate.

That year, she posted a series of videos to her YouTube channel, of her chatting on the effects of bullying, depression, body image and racism. Often, she would acknowledge that she was setting herself “up for hate”, but that it didn’t matter “if I reached one person who needed to hear those things. Depression is still something I suffer with,” she says, “but it’s something you learn how to cope with and you get help.”

Gill says she can still feel lost and overwhelmed, but she comes across as quietly self-assured. In an industry that feeds bratty entitlement and extreme privilege, she is almost disappointingly sensible. When we break for lunch – a very unfashion pasta bake and ciabatta, which she doubles down on – she chats about how much she hated the pace of life in central London in 2015, and how much more she prefers the outer suburbs of zone 4, chilling in her new-build apartment.

Shirt, skirt and boots, mulberry.com. Photograph: Gustavo Papaleo/The Guardian

Later, she struggles to think of any wild parties she’s been to. I joke that her generation have rebelled against the excess of model-standard cliches, that in its heydey, everyone assumed the fashion industry was propped up by cocaine, champagne – “And now it’s clean eating,” she says, with a laugh. “I like going to concerts with friends, but I don’t like drinking. I never liked the taste, so I don’t do it. My idea of a good time isn’t getting messy and out of control. My mum is that person at a club letting her hair down, drinking, being social. She’s like a life-of-the-party-type person. I’m much more shy.”

After the shoot, Gill changes into trackies and envelops herself in a suede camel coat. Off-duty, she likes to wear only streetwear – a comfy, easy, Yeezy-inspired aesthetic. “I never owned a pair of trainers [before I became a model]. Back then, I would have said this look was ‘trampy’.” She always looks cool now, I say, and she cringes. “God, no way. Even now, I’ll look at an Instagram from a few weeks ago and think, ‘Oh my God, why did I wear that?’”

Gill’s career is very much on the ascent; last month’s announcement that she was a new face of L’Oréal (yes, the first British Indian to do so) helped her star to rise even farther. This month she has jobs in LA, India and Japan, and she plans to spend the summer in New York, trying out for the September shows. Three years into her career, Gill is working out how to take better care of herself. She is being pickier about her jobs, making an effort to see her family more and learning to cook. “I won’t be doing this for ever,” she says. Her worst fear is becoming vapid. “I don’t ever want to be one of those girls having dead conversations.” She puts on a preening vocal fry. “Oh, what are you dooooing? So I just did Prada, mmm mmm, and I went to Milan.” Another eye roll. “I want to have depth. I want to stay normal. I love fashion, but it is a bubble. The industry magnifies things out of proportion and you need to remember what matters.”

• Hair: Bjorn Krischker at Frank Agency using Fudge Professional. Makeup: Linda Andersson using Lancôme. Fashion assistant: Bemi Shaw. Digital and Lighting Assistant: Kiran Mane