The over 80-year-old style stars

"Your body is your best friend in the entire world," says Ilona Royce Smithkin, a flame-haired nonagenarian fashion icon and one of the stars of the new filmAdvanced Style.

Royce Smithkin has many opinions about clothes - and many more about life.

"I think people expect too much of themselves, and that's not for happy-making," she explains from her tiny West Village home. "In trying to be perfect you miss half of your life."

The documentary in which Royce Smithkin appears is the brainchild of photographer Ari Seth Cohen and film-maker Lina Plioplyte. San Diego-raised Cohen founded the blog Advanced Style in August 2008, and it quickly became a sensation for showcasing one of fashion's most unjustly overlooked demographics: women over 60.

The blog spawned numerous other projects - including a 2012 coffee-table book, now in its seventh print run - and garnered praise from sources as diverse as The New Yorker and Vogue Italia, which called Advanced Style less a street-style blog than "a sociological treatise" on ageing and identity.

Marc Jacobs said the blog and its subjects inspired him to design his AW12 collection (never mind that he cast runway models as young as 14 to show it). Barneys' Simon Doonan, in the documentary, calls Cohen's photography "punk and subversive". Reading Advanced Style, one gets the sense that the women featured see dress, as one subject puts it, as a "supportive act" - that they are, through personal style, demanding to be seen in a society that too often looks past them.

The Advanced Style film follows seven stylish older New York women who are frequent subjects of Cohen's blog. Filming began in 2008, and the feature was financed primarily via a 2012 Kickstarter campaign that raised $55,441. "I pulled a lot of favours to bring the film in on budget," laughs Plioplyte.

The project started after she shot short video portraits of Cohen's subjects. "People were going crazy for them on YouTube - we were getting, you know, 50,000 views," she says. "Suddenly it seemed like the story was much, much bigger than just a video or two."

When first approached, almost all of the women who became Cohen's subjects expressed some scepticism about the blogger and his project. Retired dancer Jacquie Murdock, who recalls that she was wearing a Courreges jacket when Cohen came up to her, warned him sternly: "I'm a professional - I could sue you if you use my image without my permission."

Cohen says Joyce Carpati, now a friend and a subject of the documentary, also "took a while to convince".

"Some women say yes, and some women say no. And that's just how it is," he says. "If they're 83 years old and they're out on the street, it's because they have somewhere to be."

It's the "flat-out no's" who still haunt him. "I remember one lady on Lexington in her 60s - she had old movie-star red hair, gold belt, leopard-print jacket ..." he trails off.

Women who say no are worried about the use of their image, worried that the blog will patronise them - or they simply don't have the time or inclination to pose. One woman in her 60s who works in fashion has always turned Cohen down because she finds the project "othering" to older women.

"What I present on my blog is very positive," says Cohen, who is 32. "I don't really show the negative aspects of ageing, because that's already in the media. But in making the movie we definitely wanted to show the struggles." He becomes quiet. "It's something that we usually don't have to think about when we're young - losing friends."

Cohen, a bespectacled graduate of the University of Washington, has had an interest in the elderly since childhood. He says if he hadn't done Advanced Style he'd be working in a nursing home, and his grandmothers, Bluma and Helen, had a big impact on his early life. He describes himself as "in awe of" Bluma, a retired librarian, as a kid.

"We would watch old movies together and I would try on my grandfather's clothes and play in her cupboards," he says. Helen, meanwhile, dressed every day in Escada suits and gold jewellery. "We used to go to Los Angeles and people would ask if she was a movie star."

"My whole life has changed since I met Ari," says Royce Smithkin, a mostly retired artist and art teacher.

The 94-year-old, who walks with a stoop and makes false eyelashes out of her own orange-dyed hair, was recently a face of Karen Walker eyewear and starred in an online video for Coach. (Both ads were shot by Cohen.)

"Whatever he asks me, it's so much fun." She launches into song: "How could a lady refuse?"

Royce Smithkin - who painted the portrait of Ayn Rand that to this day adorns many editions of the author's novels - says her first awareness of style came from her mother. Born in Poland in 1920, she grew up in Berlin before the family emigrated to the US in 1938.

"My childhood wasn't a very happy one," she says. "It was a bad time. But I remember my mother always looked very nicely dressed. I was always proud of her when she brought me to school."

In another war-torn European country, a then-16-year-old Joyce Carpati had a similar first encounter with style. She was studying opera in Milan just after World War II.

"You still saw bullet holes in the buildings, and people really did not have an easy time," she recalls. "And yet in the afternoon they would come out dressed magnificently. Magnificently. I was there in the autumn and I saw a woman in a tweed suit and laced suede Oxfords ... I thought: I love that!"

She promptly acquired a tweed suit and a pair of "intelligent shoes" for herself. "And when I wore it, heads did turn," she laughs.

Carpati went on to become the first female ad sales manager at Hearst publications, where she worked for Good Housekeeping and Cosmopolitan under the legendary editor Helen Gurley Brown.

Although the film showcases its subjects' diversity - the women have very different lifestyles, they come from different ethnic and class backgrounds, and their personal styles range from colourful and anarchic to sedate and classic - common themes emerge across the seven stories. Financial struggles. Family relationships.

Dealing with ageing and loss. One of the subjects - the 95-year-old style icon Zelda Kaplan - died during production. Kaplan fainted in the front row of the Joanna Mastroianni show at New York Fashion Week and was rushed to hospital. She never regained consciousness. Another subject, Lynn Dell Cohen (no relation to Ari), was hospitalised after a ruptured gallbladder.

"I almost died," says the 81-year-old Lynn Dell. "I was on the critical list for six weeks." One scene shows her after three operations, fully made up and wearing a black off-the-shoulder top. Lynn Dell runs a boutique called Off Broadway on Manhattan's Upper West Side; she favours turbans and bib-sized necklaces. The other patients hardly share her priorities. "Some woman at physical therapy said to me: 'Oh, is this a fashion show?"' Lynn Dell says, wrinkling her nose. "I said: 'Yes, it is!"'

"As far back as when I was 3 years old, I remember playing with materials," says Debra Rapoport, 68, another of the film's subjects. "For me, everything was a hat."

Rapoport, whose snowy pixie cut is dip-dyed pink and who has been a face of Kmart, was influenced by her grandmother's Depression-era thrift - she outfitted the household in recycled fabrics, sparking Rapoport's own interest in the reuse of materials. These days Rapoport is an artist and milliner who says she is inspired by the "layers" of the city - "by concrete and garbage and residue and recycling".

Jacquie Murdock, 83, was born at the height of the Depression to Jamaican immigrants. In the 1930s and 40s, there were two gears around which Harlem style turned: church and nightlife. The teenage Murdock's parents dressed for the former, while she dressed for the latter.

"People in Harlem were very fashionable," she recalls. "I don't care what kind of menial job they had, they got dressed up on Friday and Saturday nights when they got paid, and they went to the ballrooms."

Murdock's dance costumes were fashioned from anything and everything - including, once, her teacher's mother's curtains. At 17, Norma the "Queen of Swing" Miller hired Murdock to dance at the Apollo Theatre. "I was in heaven," she says. "To go into the Apollo, to stand behind that curtain, behind that Count Basie Orchestra. When that music came up from the floor through your feet all through your body - I still remember the volume of the horns - it was wonderful."

Cohen founded his blog to help correct what he sees as a fundamental injustice of American culture: the invisibility of older people, particularly women over 60. Older women are largely unseen in the media, and - as Tina Fey once put it - any woman "who keeps talking even after no one wants to f*** her any more" is likely to be deemed crazy.

"People ask: 'Why do you mostly photograph women?' Well, I don't think men have those same challenges," says Cohen. "I think a lot of it's fear. Fear of death. Fear of getting older."

"As a group I think we have a heck of a lot to offer," says Carpati, a grandmother of two who wears her grey hair in a plait. "I hope I'm not being too strong. I really feel that way."

Lynn Dell Cohen agrees. "People are living longer and we're not going to hide in the bushes."

In the US, as all over the West, the population is ageing. There are now more than 57 million Americans aged 60 and older, according to census data, and the fastest-growing segment of the senior population is people aged 85 and over. According to a 2012 Nielsen survey, baby boomers alone are responsible for 49 per cent of purchasing decisions in America, but less than 5 per cent of advertising is directed at them.

In the United States, says Plioplyte, "I think we are way more into the idea of being female as a 'girly', sexy thing, rather than embracing women at every stage of life. I mean, an older woman is a 'cougar' if she tries to look good. I think here, more than in any other country that I know of, age is shunned."

In her native Lithuania, Plioplyte notes, older people are treated with more respect.

"The focus is on youth," says Murdock flatly. "Especially in fashion." She doesn't relate to 14- and 15-year-old models in magazines. "They look like kids dressing up in their mothers' clothes."

In 2012, Steven Meisel shot Murdock for a Lanvin campaign. "I can't afford the dress that I wore in the ad," she admits.

She lives on a fixed income in NYU faculty housing (she spent 30 years working as an administrative assistant to an NYU maths professor, during which time she earned three arts degrees). "It was a $4000 dress. Kim Kardashian bought it."

Ageing has, for these women, brought with it a kind of liberation. "We all want some kind of approval," says Lynn Dell Cohen, "but I think you have to like yourself first."

"I am not afraid," says Carpati warmly. "That's what age can do for you. It gives you a freedom! I don't care. I must sound outrageous to you, do I?" she says. "I'm free."

One of the documentary's most memorable scenes depicts Royce Smithkin in Provincetown, Massachusetts, with Karen, her friend of 55 years. Karen is suffering from dementia, and the two sit in beach chairs holding hands and belting out show tunes. Karen, says Royce Smithkin, passed away last winter.

"When you get older, you don't have to have everything," she says. "You don't have to go to every party. Life goes on just the same. When I was younger, if there were six parties, I thought I had to go to every one or I'd miss something. But now, every day living is a party."