Liberated by Coco Chanel from its traditional role as garb for servants and mourners, the little black dress has ever since been an essential for every woman. Now a collection by Edinburgh College of Art is celebrating its many forms

AUDREY HEPBURN munched on a pastry outside Tiffany's in hers. Anita Ekberg wore hers to frolic in the Trevi Fountain in La Dolce Vita. Betty Boop's was cut short enough to show her garter, while Elizabeth Hurley's was held together with safety pins. Edith Piaf wore hers, initially, because it was all she owned.

Yes, the little black dress has come to the rescue of countless women since Coco Chanel debuted her first design in 1926, describing it as "the new uniform of modern women". Today around 96 per cent of women in Britain own at least one, and one in every two dresses bought is little and black.

So enamoured by the little black dress is Roz Colthart, from Blackhall, that three years ago she set up www.Black-Essentials.com, an online business devoted entirely to providing black clothing for women. She's a connoisseur, then, but even so, when she set second-year fashion students at the Edinburgh College of Art the challenge of designing the perfect little black dress, she was blown away by their work.

Each student has produced a prototype little black dress, and the winning design – which will be announced at the ECA's annual fashion show on 7 May – will be available to buy through the website. Students were told the fabric used could cost no more than 6 a metre, but beyond that were free to let their imaginations run wild.

"Judging this has been really difficult," says Colthart. "The students really rose to the challenge, and I think they really enjoyed the brief. There's just something about little black dresses, isn't there? There's this idea that your wardrobe can survive any occasion if it's got a perfect little black dress in it. The right one is timeless, classic and flattering, and it's the one colour that all women will reach for every time."

It was not always so. Prior to Chanel's innovation, black was a colour associated with both servants' uniforms and mourning widows. Couturier Paul Poiret, a contemporary of Chanel's, declared the little black dress to be "poverty de luxe", dismissing it as "small, undernourished and telegraphic". Fashion legend has it that when the pair met on a Paris street, Poiret asked, "For whom, madame, do you mourn?" to which a black-clad Chanel replied: "For you, monsieur."

The trend for the little black dress – LBD – was one of many set by Chanel that remains a staple of women's wardrobes today. At the time, Vogue dubbed it "Chanel's Ford" because like the Model T car, it was simple, classic and accessible for women of all social classes; fabulous "in any colour as long as it's black".

Since then, fashions have come and gone, but designers will almost always include an LBD in each of their collections. They have to, really. Wallis Simpson, the Duchess of Windsor, hit the nail on the head when she said: "When the little black dress is right, there is nothing else to wear in its place." Actress Joanna Lumley has said that her favourite Jean Muir LBD "transformed my life utterly". Supermodel Erin O'Connor says: "When I travel I always pack a little black dress. It's like a blank canvas that can be dressed up or down, whatever the occasion. I think when you buy your first LBD, it's a sure sign you've grown up."

"When you find a truly great little black dress, you'll have it forever," agrees Kevin Stewart, a stylist with Harvey Nichols in Edinburgh. "It will transcend trends and no-one will ever say, 'Oh, she's wearing that same dress again,' because it simultaneously stands out, yet stands the test of time. Designers usually include at least one LBD in each collection, and they're perennially popular in Harvey Nichols. Prada are always great for them, but my favourite one this season is by Balenciaga, with a silk bow at the back and a tight bodice."

For some designers – Azzedine Alaia, Cristobal Balenciaga and Yves Saint Laurent included – the LBD was often a cornerstone of their collections. US designer Donna Karan has even admitted: "I built an entire company around a little black dress concept. With black, you are the 'It' versus wearing the 'It' dress. A colour or pattern does not distract the eye from you."

Some LBDs have become icons in themselves. The Givenchy number Audrey Hepburn wore, cheekily accessorised with a cigarette holder and a Danish pastry, in Breakfast at Tiffany's sold at auction for more than 500,000 in 2006.

When Princess Diana made her first public appearance following Prince Charles's admission of adultery, she wore a sexy black Christina Stambolian number, which came to be known as the "revenge dress".

French singer Edith Piaf had a penchant for performing in a basic black sheath that became a visual trademark. Her reasoning – which would not be unfamiliar to Donna Karan – was said to be that the simplicity of the dress would help audiences focus more on her singing and less on her appearance.

At the Edinburgh College of Art, students have responded enthusiastically to their design brief with a broad range of creations, from corseted mini-dresses to A-line shift dresses, across the 18 final submissions.

Highlights include a suede shift dress with a sheer panel and leather roses by Riona Horrox, and a wonderfully modern affair with an asymmetric embroidered design on the chiffon shoulders by Farrah Saffari.

"I have a vast collection of little black dresses, but I was really impressed with the sheer variety in the students' designs," says Colthart. "It just shows how versatile the little black dress really is.

"There can be so many different interpretations of it, and designers with all sorts of different visions can turn their hand to it. I'm thrilled with the results."

&149 The Black Essentials/Edinburgh College of Art collaboration will appear on the catwalk as part of the Edinburgh College of Art Fashion Show from 5-7 May.

Tickets are available through Hub Tickets: 0131 473 2000; www.hubtickets.co.uk