LONDON — The lineup of designers was impressive by any fashion standards — exemplified by the suave and seasoned Oscar de la Renta alongside the lithe and youthful rising star Gareth Pugh.

Other celebrities stood by an exhibition of life-size photographs of themselves in vintage clothes, with all these famous names, including Sir Philip Green, founder of Top Shop, clustered around fashion’s “Queen Bee.”

Make that “Mrs. B,” as Joan Burstein is always known. Her Browns boutique — an incubator of talent for four decades — celebrated 40 years in fashion this month.

With gold balloons floating overhead in a penthouse suite and the hostess in a sparkly Lanvin dress, the event was a joyous celebration of the Burstein family who brought so many unknown names to London (think: Giorgio Armani and Ralph Lauren) and introduced them across the globe.

“I first met her in 1970-something — and we still work together,” said Rosita Missoni, while her daughter Angela confirmed the date as 1971 and said of Mrs. Burstein: “she never dropped the collection — not for a single day.”

“Browns is such an important part of anyone who loves and adores fashion,” said the former model Yasmin LeBon, who posed for the photographer Paulo Roversi in a Ralph Lauren skirt (with her upper body naked) for the illustrated book that marks the birthday moment.

“By learning through Vogue, the only street I knew when I came to London was South Molton Street,” said Ms. LeBon. “It’s always been my radar.”

South Molton Street was a row of town houses off Oxford Street in London, with the iconic shop founded in the “swinging 60s” by the aristocrat-turned shopkeeper Sir William Pigott-Brown. It was while Simon Burstein, now the company’s CEO, was a student working at Browns as a Saturday job, that he fell in love with the lush, colorful, velvet Newman jeans — and begged his parents to buy the business when it came up for sale.

Sidney Burstein, who died last month, worked with his wife and children to make the store and its subsequent line-up of other shops into a Mecca for smart retailing — not least when Mrs. B bought up the fledgling designer John Galliano’s entire graduation collection from Central Saint Martins school, and put it in the windows.

“And they were the first people who spotted my college collection,” said Hussein Chalayan at the celebration. “They gave me the window in March 1994 — 10 years after they had given it to Galliano.”

In this current millennium of global, cookie-cutter stores, it is hard to believe that Browns and the peppering of other imaginative boutique owners, such as the Hong Kong-based former retailer Joyce Ma, made the whole designer fashion thing happen.

“From the day I first met her, I knew that Joan Burstein was an authentic risk taker,” says Ralph Lauren in the book’s foreword, as he remembered the independent shop the Bursteins created with him as “the first American designer boutique in Europe.”

Mrs. B famously accosted Calvin Klein on the dance floor at the hip Studio 54 in New York— and begged him to sell to Browns. (She succeeded.) And even before her daughter, Caroline, had set up “Browns Bride” or Simon had married Sonia Rykiel’s daughter, Nathalie, the shop had garnered a worldwide reputation. It sold designers such as Azzedine Alaïa, Walter Albini, Cacharel, Ossie Clark, Jean Muir and Antony Price.

If Simon Burstein had not developed an e-commerce site, following his career at Rykiel, Browns might have risked drowning in the wake of designers’ own mighty flagships. But the store is still buzzing and the presence of designers like Erdem Moralioglu proved that young talents are proud to be given the Browns seal of approval.

“They took the full collection 2009 and it was very exciting to get with Browns” said Mr. Moralioglu. “In a way the clothes out of the show context is the reality.”

Although so many multibrand boutiques have disappeared with the retirement of the founders, Mrs. B herself is still an active member of the team, some of whom have been with her from the beginning. And the fact that her granddaughter, Charlie Collis, has entered the business makes her confident about the future.

“I am very grateful and very proud,” Mrs. Burstein said. “And I know my granddaughter is going to make it.”

SUZY MENKES