Shortly after they were married, Batsheva Hay was startled to find her husband, the celebrated fashion photographer Alexei Hay, throwing out all his old clothes. “He had such cool clothing, really super stylish three-piece suits, things like that,” she recalled one recent afternoon as we sat in her apartment in Manhattan’s Upper West Side. Hay tried to save a few pieces, but Alexei would not be persuaded. Although brought up as a secular Jew, he’d recently turned to Orthodox Judaism, and wanted to purge his wayward past. Those clothes had been worn around other woman, and therefore had to go. Hay was dismayed. “He literally threw everything away, and went to a tailor in Williamsburg and just had 10 Hasidic suits made and started wearing those to photo shoots,” she recalls. “It was crazy.” She scrolls through her iPhone to find photos of Alexei in his full beard, black fedora and plain black suits – and giggles. “He just rolled like that for a while, and meanwhile I was wearing leggings and T-shirts. We looked like such an odd couple.”

Bonkers though it may seem, it takes a certain kind of confidence to turn up to photograph someone like Prince Harry for Town & Country, or Sarah Jessica Parker for the cover of Bazaar – two of Alexei’s many commissions – dressed in full Hasidic garb. In an industry constipated by the relentless demands of holding the right pose, it even feels radical. Like the scene in Annie Hall when Woody Allen morphs into a caricature of a rabbi at the dinner table of Diane Keaton’s all-American family, it forces others to examine their uneasiness. “Alexei has to really believe in something and take it to the nth degree,” explains Batsheva. “And he’s also happy to provoke people, and say something that makes them uncomfortable. I’m not, I’m a people-pleaser.”

Hay, the daughter of secular Jews who met on a kibbutz shortly after the Yom Kippur war, didn’t share her husband’s spiritual quest. But his new-found religious ardour presented her with a knotty challenge. How could she dress for the Sabbath without sacrificing her style? The answer, she realised, lay in the floor-length vintage Laura Ashley dresses she liked to hunt down at second-hand stores. With their high, embellished collars and long sleeves, the brand’s mash-up of Victorian pastoral and exaggerated femininity enabled her to follow rules while subtly bending them to her will. Without Alexei’s religious odyssey, you could argue, Hay’s second career as one of New York’s most heralded designers might never have happened.

The frill seeker: Hay at the Vogue Fashion Fund Awards ceremony in New York in November 2018. Photograph: Andrew H Walker/WWD/REX/Shutterstock

If, like others, you too have consigned Laura Ashley to punchlines about 1980s consumer culture and class fetishism, Hay may give you reason to think again. For Brits who can still recall the era, Laura Ashley’s floral froufrou, like Aga stoves and pot pourri, often felt like accessories for a lifestyle preoccupied with a certain kind of status, exemplified by a Cotswold cottage furnished with chintzy wallpaper and fabrics. But fashion has an extraordinary ability to quote from its greatest hits while simultaneously subverting them. Meanings shift and change.

Hay grew up in Queens, New York. As a child, she took pleasure in the label’s exaggerated romanticism, its whiff of theatricality. The clothes felt like an extension of the school plays she enjoyed performing in. She had the sheets, the bedspreads, the sailor dresses, even the straw hats bedecked with ribbons.

“I’ve worn Laura Ashley my whole life,” she says breezily, as she pulls her feet on to the sofa in the modest New York apartment she shares with Alexei and their two children, Ruth and Solomon. Toys litter the floor. A dead rose sits forlornly in a Mason jar. Hanging on a wall is the 10 Commandments etched on to a wooden tablet, among the few concessions to decor. It’s the home of people who don’t care much for material possessions. There is no Aga, nor will there ever be.

The leap from wearing vintage dresses to using them as a basis for her cut-and-paste sensibility came in 2016, when Batsheva took a corduroy floral dress she’d found to a dressmaker, altering the shape to make the sleeves puffier, the waistline higher, and using vintage fabrics she found online. It was a 35th birthday present to herself, but when friends asked her to make dresses for them, too, she began posting photos to her Instagram account. Intrepid buyers for a Japanese store quickly noticed her work, and got in touch. “I just went to their hotel room with my four dresses and they ordered a bunch,” she says. “I didn’t even have a business Instagram at that point.”

Back to his roots: Batsheva with her husband. ‘It’s possible to argue that without his religious odyssey, her second career as one of New York’s most heralded designers might never have happened.’ Photograph: Madison McGaw/BFA/REX/Shutterstock

Her rise has been swift. This past September, a day after she presented a collection for New York Fashion Week in a Manhattan diner, where models wore hairnets and passed out milkshakes and fries, the online magazine Quartz declared that: “The fashion media is, frankly, batshit for Batsheva.” A profile in the New Yorker that same month described her style as “both subversive and coveted”. The New York Times singled her out as an avatar of a trend it has dubbed “urban pioneer girl”. Andie MacDowell’s daughters are apparently big fans. So are Natalie Portman, Erykah Badu and Lena Dunham. Recently, Hay received a text from Nick Ashley, son of Laura and Bernard. “I love the way you have picked up the baton and made [her look] your own,” he wrote.

The Batsheva look might be described as falling somewhere between Julia Louis-Dreyfus’s nerdy Elaine on Seinfeld, and Mia Farrow in Woody Allen’s Hannah and Her Sisters, with a touch of The Golden Girls with their unabashed love of metallic brocades and a high ruffle neck.

“Mia Farrow is my dream woman,” Batsheva says when presented with the comparison. “The women in Woody Allen’s movies dress like my grandmother dressed, so it is sort of my culture, and always with me.” Although her dresses can seem old-fashioned or nostalgic, they can also seem playful or severe. In many ways, Batsheva’s grandmother is the animating spirit of the brand. “She had this frumpy New York aesthetic, but she also wore this brand that obviously wasn’t New York Woody Allen, and yet the contrast worked,” she recalls.

In a subsequent conversation, Alexei amplified the point. “When someone says they are dressing for themselves, there’s many layers to that,” he said. “I think that Batsheva is imitating her grandmother – she wants a connection to her through her dresses.”

Queen of the cover-up: ‘I think Batsheva is imitating her grandmother,” says her husband. ‘She wants a connection to her through her dresses.’ Photograph: Alexei Hay/The Observer

Every successful business has an origin story. Hay’s is all the more striking because her rise has been so rapid, and because her new career was the result of chance, not design. “I tell people it’s a fashion fairytale,” Hay’s mother, Gail Rosenberg, told me as she ferried her grandchildren home from school one afternoon. Hay had always been close to her grandparents, Rosenberg said, but it was her grandmother, who grew up in the Lower East Side speaking Yiddish, who passed on her sense of style.

“During the 50s and 60s she dressed very conventionally, kind of like Jackie Kennedy,” Rosenberg said. “As she got older she became a little bit bohemian, left her hair natural, wore peasant dresses, Bohemian ethnic fabrics, embroidery, things like that.”

In different but vital ways, Hay was also influenced by her lawyer grandfather, Henry Rosenberg, who died only recently. There are two photographs of him in the bedroom of Hay’s apartment, one with Al Gore and the other with Bill Clinton, beneficiaries of his fundraising energies. Henry Rosenberg was born in Paris in 1929 and largely raised in foster homes, his life a font of stories featuring derring-do, from working with ex-convicts and helping Ethiopian Jews escape to Israel in the late 1970s, to fighting for Native American land rights, and hitching a ride through the south on a truck to record the plight of American working men. He was in his 80s by then, and Hay says the drivers had to fight to keep him from joining in the manual labour. “He always made me feel that it was important to have adventures, and to try things out,” she says. “It was just something that came naturally to him, without worrying about it too much.” She gestures to the overladen rack of dresses in her bedroom. “He loved this – he was so proud of me.”

Although she plays it down, Hay’s decision in 2012 to quit her “stuffy white shoe firm”, where she had worked as a litigator, was very much in the mould of her grandfather. It also marked a period of self-examination that paralleled some of her husband’s journey. “She rebuilt her whole life after she stopped being a lawyer,” Alexei told me. “She questioned everything. Who are these people to tell me what to do? Who are these people to tell me what to wear? There’s something very fierce about it, and it comes from a real question: what’s going on here? And I think that resonates with women at the moment.”

‘I just thought: Even if no-one buys this, it’s worth it because I’m making my own wardrobe’: Hay and a model present her Batsheva spring/summer 2019 fashion show. Photograph: Jonas Gustavsson/SIPA USA/PA Images

Hay tiptoes gingerly around the suggestion that her whimsical mission to rehabilitate a beloved vintage dress is now that real and elusive thing: a fashion brand with prospects. “I’m so risk-averse that I didn’t want to say it was going to be a business or anything,” she says. “So, every time I designed another dress I just thought: ‘Even if no one buys this, it’s worth it because I’m making my own wardrobe.” She turns to a young New Zealander working at a laptop at the kitchen table. “Grace, when did this become a business?” she asks. Grace, who has been working part-time for Hay since June, furrows her brow and thinks. “It’s just you, me, and Lulu,” she replies. Lulu is the intern. “She helps me with everything,” says Hay.

It seems unlikely that Hay will be managing her business from home for much longer. Demand has grown especially brisk since the summer, when she was named as a finalist for the prestigious CFDA/Vogue Fashion Fund, for which she was awarded $150,000. Since then, orders have been flooding in from new clients, such as Galeries Lafayette and the online retailer matchesfashion.com, where her dresses sell for around $425. Natalie Kingham, the buyer at Matches, told me that Hay’s clothes have a cross-generational appeal, and are easy to layer. “Women feel very nostalgic in her prints,” Kingham said, but added that Hay’s subversive styling also gave the clothes “a modern edge”.

Fashion writers love to champion a trend, and Batsheva’s diner show has fuelled a spate of stories musing on the rise of “prairie fashion”, a term she finds a little offputting. “I like the idea of the frontierswoman,” she says. “It’s this weird place of using these very old-fashioned, almost kitschy styles, and then being tough with them.” Where she may part ways with Laura Ashley is in imagining the kind of person who might be drawn to her designs. “I feel it looks really good worn on someone who’s a little bit androgynous and wearing sneakers,” she says. “This is not really the dress for Pamela Anderson or Kim Kardashian.”

While there is always a social context for the way people choose to dress, Batsheva is wary of looking for significance where there might be none. Some women like long dresses. Can that also be part of a #MeToo retort to the hypersexualised sensibility of male designers? Maybe, but maybe not.

“I respect that perspective in some ways, but I also feel like that conversation is still within that same paradigm,” she says. “You’re either accepting or rejecting the idea that men want you in this clothing. I always felt that this was how I should dress, and I always did dress like this when I was younger, and maybe it’s resonating more widely now because of women reclaiming how they want to look and pushing away from a lot of what these largely male designers are telling them to wear.” She shrugs. “I don’t know if that’s an answer.”

The afternoon is turning into evening, and Ruth and Solomon have returned from their local Jewish school. “Did you make challah bread?” Hay asks Solomon. He nods shyly, and brings his bounty forward to cries of admiration. Soon it will be time to light the Friday candles. Although initially hesitant, Hay now enjoys many of the Sabbath rituals she once resisted. Instead of shopping, Saturdays are spent in reflection and meeting friends. She does not use her phone. “It really does help me let go of things,” she says. “I used to be embarrassed about it – if someone invited me to a birthday in Brooklyn on a Friday night, I’d say, ‘Sorry I have plans,’ but now I just shrug and say, ‘Shabbat.’”

When she ventures to downtown Manhattan these days, Hay is starkly aware of the way fashion imposes itself like a uniform. “Everyone is trying so hard to follow the trends and be so put together, whereas up here there are so many weird old people wearing crazy stuff,” she says. “It’s why I love old people. They don’t care. It’s way more punk than people in the East Village trying to look punk by copying an album cover they saw.”

Accompanying Alexei on visits to the Hasidic enclave in Williamsburg in Brooklyn, she is inspired by the unselfconscious way the women wear their clothes, their unforced originality, the absence of preciousness. All those unrepentant shoulder pads!

“I’m not interested in these downtown people wearing all black,” says Batsheva. “I’m going to wear my insane terrycloth nightgown that I bought in Williamsburg that’s way cooler than all of this.”

Does she actually have an insane terrycloth nightgown? “I have a few,” she says, her mouth creasing into a smile. It’s easy to imagine her grandparents, somewhere offstage, smiling along with her.