LONDON — Early on a Friday evening not long ago, the fashion stylist Sarah Edmiston Price was on the second floor of the Notting Hill townhouse she uses as an office, happily picking through a rail of her favorite vintage finds. She flipped past a shimmery putty-colored Tom Ford for Gucci jacket and a hand-painted Dolce & Gabbana gown and pulled out a slinky electric navy dress by Roberto Cavalli.

“Oh God, this is so good,” Ms. Price said, holding it up to admire. “Someone in the next year will wear this.”

To the Oscars, perhaps? If so, you will never find her tagging the wearer on her Instagram, or posting a behind-the-scenes Story that would unmask the whole operation. (Remember when the great mystery of Kate Middleton’s wedding dress designer, Sarah Burton of Alexander McQueen, was solved, in part, by a distinctive leather-studded belt?)

“It’s a shame for a lot of these women with the Oscars that the designers are going ‘We dressed her!’ And the stylist is going: ‘I did it’ and there’s no honoring of a woman’s taste and the woman’s input,” Ms. Price said. “It’s just these big brands paying big bucks to be worn, to be tagged, to be advertised, to be billboarded. I think it strips her of a bit of her dignity.”

Ms. Price, who declines to give her age, speaks with a soft Irish accent, often with long pauses between words, like she is about to impart a big secret. Except she isn’t.

She never talks about her 28 clients, who include Princess Eugenie, actresses, models, high-profile businesswomen and “different royal families around the world.” (Asked about Eugenie specifically, she held a finger to her lips and smiled.) She shuns freelance help, personally chooses her couriers, and snaps photos of “my women,” as she calls them affectionately, only from the neck down, lest any images go astray.

Though she is praised in fashion circles as having elevated Princess Eugenie’s style — headlines even before the princess’s wedding in 2018 talked about how the ninth in line to the throne had “wowed the crowd” and “nailed it” — Ms. Price would never claim credit.

“That’s not really fair to her,” she said, referring to any client, “because she’s the one who has to carry the look.”

Sitting at the foot of her desk on the townhouse’s ground floor, Ms. Price was drinking green tea she had served in pale flowered cups with saucers, her rescue puppy Edie (named for the renowned costume designer Edith Head) snoring gently in her lap. Ms. Price looked elegant but not intimidatingly so in black-patterned trousers from The Kooples, a cream cashmere jumper bought at a sample sale in New York, and a vintage Cartier watch of her father’s. She took off a Dior astrology scarf she’d hoped would hide a psoriasis flare-up, pronouncing it “too air hostess.”

Ms. Price works by referral only, preferring women who want to use clothes to change the way they want to be perceived: like an actress marooned in sweet period pieces who wanted to transition to, as Ms. Price put it, “roles where she’s potentially going to run through the woods with a crossbow.” (Ms. Price injected more leather into her wardrobe and added some chunky rings and dark nail polish.)

Samson Dougal, an alumnus of Alexander McQueen who works frequently with Ms. Price, said: “There’s always a deeper message with her. She does so much more than just pulling clothes.” Mr. Dougal, whose designs for Princess Eugenie include the pale blue ’60s-inspired dress she wore to Meghan Markle and Prince Harry’s wedding and a pale pink silk biker jacket she wore the day after her own wedding, first worked with Ms. Price four years ago on a dress for “another princess. She has endless princesses,” he said.

Emily Baxendale, one of Ms. Price’s go-to milliners, said: “With a lot of stylists it’s like, ‘Do you have this? Yes or no?’ With Sarah there’s always a vision — where are we now and where do we want to be? — and you end up designing a new piece.” Feathers, flowers, and any kind of mad hattery (like the pink pretzel-like topper Eugenie wore to William and Kate’s 2011 wedding) are never part of the brief. Ms. Price likes hats to accent, not dominate. (Her circle is very close, Mr. Dougal said, and when anyone falls short of her high standards, she chides them with: “That’s not how we do things in this family.”)

Ms. Price’s days sometimes begin at 4 a.m., because a client’s only free moment is en route to Heathrow when she has just finished a film and decided last-minute to attend, say, Coachella. (She has learned to keep a rail of clothes in multiple sizes, plus sandals and wedges, ready for festivals.)

Ms. Price grew up “no style heroine,” wearing a bottle-green wool uniform and Benetton jumpers to the local convent school in Dublin. She had always loved photography and design, but it wasn’t until a bout with the flu at age 21 — when she spent five days in bed paging through fashion books, including “A Century of Couture” and Rachel Zoe’s “Style A to Zoe” — that she decided: “I’m going to make fashion the thing I’m really good at.”

In 2006, she moved to New York to attend the Fashion Institute of Technology, got a job as an assistant at the then-recently-revived Halston (Ms. Zoe was the label’s creative director), and picked up her first client there, the wife of one of Halston’s investors.

She spends hours getting to know the subsequent ones, first over lunch. Then there is a closet riffle, which usually reveals when someone thinks she was her best-looking. Ms. Price cited a client in her 30s who still had a wardrobe full of low-slung combat pants.

“It was her peak in her mind of her flattest stomach and her most beautiful her,” Ms. Price said. “It’s my job to convince her that her peak actually is in front of her.”

In between fittings, she communicates with clients (and their staffs) via a flurry of WhatsApp messages. The word “urgent” is to be saved for — here Ms. Price paused to choose her words carefully — a dress that has arrived somewhere with multiple entrances, and been signed for, yet no one can find it.

“Often we’ll do things that are secrets, and we’ll send it all in white packaging, white garment bags, all unmarked,” Ms. Price said. “So if it goes to the wrong gate, we’re now looking for a thing I don’t want anyone to find.”

And now, a secret about Ms. Price: The clandestine way she works suits her as well as her clients. She is a homebody; not a fan of fancy parties and fashion shows. She whispered when she admitted the latter, adding, “They vibrationally disrupt me for, like, an entire day.” (One way Ms. Price recovers: watching films with the sound off, so she can better appreciate the fashion.)

Her discretion also keeps her from the career-limiting problem of being associated with any particular style. “I like to think if all my women ever were together in one room, they’d be like, ‘Oh my God, really?’” she said. “It keeps my fashion muscle working.”

She does have a few go-tos, like capes (“or a cape kind of drama,” Mr. Dougal said), and is partial to a low back, as on Princess Eugenie’s Peter Pilotto wedding gown, even if the client complains she is too flabby, mole-covered or pale for one. Ms. Price does not believe in problem areas. She tells her women: “Your problem area is between your ears.” Still, she will never talk anyone into wearing anything.

“My God, I’d rather die,” she said.