There's only one problem with staging a major exhibition on Barbara Hulanicki – editing it.

Not just a 1960s fashion icon, the Biba designer has also created wallpapers, interiors, artwork, even baked bean tins.

“It’s hard to know quite where to begin,” says a slightly bewildered Martin Pel, the curator mounting the show.

We’re in the basement of Brighton Museum, where he’s currently sharing his office with a bevy of modish young women in various incarnations of the “Biba look”.

One of the mannequins is wearing an early lace mini-dress featuring John McConnell’s famous “celtic knot” design that would come to define the brand’s identity and packaging; another is dressed in a bronze brocade waistcoat dress.

Then there is a T-shirt from the 1980s printed with one of Hulanicki’s distinctive black and white fashion illustrations and a floaty blue chiffon number from her 2009 collaboration with Topshop.

Emotional attachment “We’ve been really fortunate to be put in contact with two of the biggest Biba collectors in the world,” says Pel. “Between them, they have about 3,000 pieces. But we’ve also had loads of individual donations – people phoning us to ask if we’d like the Biba dress they wore to their graduation or their prized Biba carrier bag. There’s a really strong emotional attachment when it comes to Biba.”

It’s no exaggeration to say the brand revolutionised the British high street and, to some extent, women’s lives, offering affordable, accessible fashion at a time when it didn’t really exist. It started life as a postal boutique whose first significant success was a pink gingham dress that looked a little like one worn by the actress Bridget Bardot. The day after it was advertised in the Daily Mirror in May 1964, Biba had received more than 4,000 orders. They would go on to sell around 17,000 of the dresses.

Later that year, Hulanicki and her late husband Stephen Fitz-Simon (known as Fitz) opened the first Biba store in Abingdon Road, London; within a decade they had taken over a seven-storey department store on Kensington High Street. It was one of the first “lifestyle” stores, where shoppers rushed to buy everything from baby clothes to playing cards, cutlery to cushions – anything to get a piece of the glamorous, decadent Biba style. At the centre of it all was Hulanicki, a striking blonde who found herself so busy she barely noticed the rock stars and models darting in and out of the changing rooms.

The exhibition aims to tell her story alongside that of her work. Born in Warsaw to Polish parents, her father Witold was assassinated in Palestine when she was 12 and she and her two sisters Beatrice and Biba were brought to Brighton by their aunt Sophie. Her aunt lived in a suite at the Hilton Brighton Metropole where Hulanicki and her sisters would be sent every weekend to be taught about “life and manners”.

They would arrive at 1pm “on the dot” and be led through for lunch before being made to read aloud and taught elocution.

At 5.30pm, her aunt would change into a gown and “fake jewellery” for tea.

“The real jewellery would come out from the safe at dinner, especially if someone was coming – so there would be another change.”

Barbara was not fond of her controlling aunt and when she eventually escaped Brighton for London, her aunt wrote to tell her she had left all the money the family had saved together to a charity. But her aunt proved a significant influence on her work; the 1930s couture she would wear for dinner – which the 12-year-old Hulanicki thought awful – eventually found its way into her designs, which blended old Hollywood with Art Deco and Victoriana. “When I look back on them now, they were beautiful clothes.”

After studying at Brighton School of Art (now the University of Brighton ), Hulanicki won a London Evening Standard competition for beachwear and thus began a career as a freelance fashion illustrator, working on Paris fashion shows for magazines including Vogue, Tatler and Women’s Wear Daily. It was this period, says Pel, that honed the visual memory that means, even today, she can remember every garment she’s ever designed.

“Illustration was important then,” says Hulanicki. “There was no photography in those days. You had to go in and remember what you had seen. I would have to go quickly and draw everything I had seen from memory. Going to a Dior show and having to watch 40 black short dresses – it was so boring, with a little sleeve here and little opening there, or two buttons! But we would have to remember each look.”

They opened the first and only Biba store outside London in Queens Road, Brighton, in 1965 – the building is now home to fair-trade clothing boutique Fair.

But it was a short-lived enterprise, closing two years later. Brighton in that period was not the city it is today and Hulanicki remembers the road as “quite rough. People would regularly walk out of the shop with stuff and the staff couldn’t care less”.

When Biba closed in 1975, Hulanicki never looked back, says Pel. “While everyone else has treasured their Biba, Barbara herself hasn’t kept very much at all because she moves on all the time. She just gets on with her next project.”

She currently lives in Miami, a city she is credited with helping revive through her design work on its Art Deco buildings. She also designs hotels in Jamaica and the Bahamas for Island Records owner Chris Blackwell and has produced wallpaper for Habitat and Graham & Brown featuring her famed art nouveau designs. In 2009, Topshop launched a collection of her designs which sold-out almost instantly and was soon changing hands for vastly inflated prices on internet auction sites.

Inspirational Incredibly, Brighton Museum’s exhibition is the first to attempt to cover the entirety of Hulanicki’s life and work, which saw her made an OBE in this year’s honours list for services to the fashion industry.

“I’d had it in mind for a long time,” says Pel. “She has all these connections to Brighton and she’s such an icon. Everything she’s done, she’s done it to the max – the interiors were incredible, the clothes were incredible – and she’s just as creative today. I think she’s really inspirational.”

He returns to his earlier dilemma – how on earth do you start to pare down collections of more than three million items?

“We asked Barbara to choose her ‘Biba look’. She’s gone for a 1968 jacket with skirt in blue polka dots which is quite iconic and she chose a big leopard print coat and hat which Twiggy wore to an opening – there’s an amazing image of her standing in front of the Biba changing rooms actually. But it’s hard to say definitively what Biba was; it means so many different things to so many different people.”

Biba and Beyond: Barbara Hulanicki is at Brighton Museum and Art Gallery from September 22 - April 14, 2013.