Last year, while staff at the V&A were researching its major retrospective of Mary Quant, which opens next month, they launched a #WeWantQuant campaign, appealing to the public for clothes they might be willing to loan or donate. “We were overwhelmed,” the show’s co-curator, Jenny Lister, recalls: “We had more than a thousand emails from women – some friends of Quant’s and members of the bohemian circle to which she belonged – but most were ordinary women. Former students, teachers and nurses – some got in touch with us from as far afield as San Francisco and Australia.” One woman – and this makes Lister laugh with delight – described taking her Quant dress to Antarctica, to wear at the south pole. Some have hung on to their makeup (such as the eyeshadows Quant’s husband and business partner, Alexander Plunket Greene, jauntily dubbed “jeepers peepers”). The collective message was that Quant’s clothes were more than just clothes, they were cherished clues to the past. In the end, the museum could only make space for the offerings of 30 women (four of whom are interviewed below). But for everyone who lived through the Quant era, this show will be a form of time travel – back to the 60s and 70s and the coolest of surnames (that Q had kudos) and the simple daisy logo that kept on blossoming.

Mary Quant (centre foreground) launches her footwear collection, 1967. Photograph: PA

In a new foreword to her first autobiography, Quant by Quant (1966), Mary Quant remembers: “Life was a whizz! It was such fun and unexpectedly wonderful despite, or perhaps because of its intensity… we were so fortunate with our enormous luck and timing. We partied too – there were no real boundaries.” Her written style – ingenue enthusiasm – matched her clothes. For Quant, fashion was “a game” and her son, Orlando, (writing In the V&A’s catalogue) acknowledges the fun his parents had after they met as art students at Goldsmiths. He remembers how his father made life “riotously exciting”. He recalls people saying: “But Mary, you can’t do that…” (an invitation to go ahead). He also argues that his mother’s designs were more serious than her modest account of them, that they brought about an “attitude revolution that changed much more than fashion”.

At 89, Quant still sticks to her original line. “I loved wearing the clothes which I designed for like-minded friends and for myself,” she tells me by email. “They reflected the sense of freedom that we felt at the time – shorter skirts allowed mobility, to run, jump and to have fun in. As I get bored quickly, I was always seeking fresh inspirations so if they worked on me, then they would provide fashion for everyone who enjoyed the styling, the crazy accessories and the cosmetics.”

Lister emphasises Quant’s prescience: “She used clothes to demonstrate that change was coming. Fashion was no longer about couture, it was about expressing individuality.”

Satin mini-dress and shorts by Mary Quant, 1966. Photograph: © Duffy Archive.

She saw that fashion “anticipates” and her design revolution grew out of a drab, postwar Britain on the brink of social change. Quant became a public figure and, as Lister says, “expressed the way in which women’s lives were parting from traditional stereotypes. Her clothes provided a language to express the empowerment of women at a time when words like sexism had barely been invented.” The designs were also Quant’s personal rebellion, her way of avoiding becoming a grammar school teacher (the fate her university-educated parents, who hailed from Welsh mining families, had imagined for her when they raised her in Blackheath, London).

Quant became an apprentice at a Mayfair milliners after leaving Goldsmiths. Bazaar, her first shop, opened on the corner of Markham Square and King’s Road, Chelsea in 1955, but it was in the 60s that the brand took off in a seemingly unstoppable way. It was a period all about energy – in the arts as well as fashion. Lister suggests that Quant’s “generosity and drive to make fashion accessible through mass production reflects a better quality of life becoming more available in the postwar period. Her clothes, as they became widely available, expressed the disruption of class hierarchy as well as gender roles.”

These were feel-good designs for women – to give them freedom, to enhance their lives

Part of the strength of the Quant brand was that she did so much of the modelling herself (as had Coco Chanel and Elsa Schiaparelli before her – both of whom were inspirations).

Photographs of Quant, with her 1920s-bobbed hair, show how she liked to keep a woman’s upper half demure: Peter Pan collars, rollnecks, zip-ups. Cleavages never featured. The models are all leg and attitude and teasing hem-lines; they had a playful, gamine quality – a freedom.

“She did not want to grow up,” says Lister, “the clothes wanted to keep childhood going but that became a new kind of sexiness, defined by her.”

In terms of inventing the mini-skirt, Quant shares the honours with the French designer André Courrèges. Some insist he got there first, in 1964, but it was Quant who put the mini-skirt – and hotpants – on to the streets. There is an amusing anecdote in her autobiography about a trip she made to a hotel in Malta in the brand’s earliest days (to recover from overwork). She was wearing a mini-skirt before they had been accepted in London, let alone in Malta: “The women glared at me. The men tried to pick me up.”

Yet, roll on a year or two, and this is how Alexandra Pringle, now the editor-in chief of Bloomsbury publishing house (quoted in the catalogue), remembers the anything-goes-exuberance of the King’s Road: “Big floppy hats, skinny ribbed sweaters, key-hole dresses, wide hipster belts… white lip-sticked lips and thick black eye-liner, hair cut at alarming angles, op-art earrings and ankle length white boots.”

And let us not neglect to mention the gorgeous coloured tights (which Quant pioneered, and which got an extra showing thanks to the mini-skirts), the PVC zip-up macs in purples and reds, the dresses that playfully doctored men’s suits – all were defined by humour and classlessness.

The clothes were not cheap – they cost about twice as much as you would pay at Marks & Spencer – but neither were they couture. Quant believed in fashion for the masses – you could even sew her designs yourself from Butterick patterns. From 1962 onwards, her clothes were produced in democratic multiples of 1,000, but many of the details did not seem mass-produced at all: groovy zips, contrasting top-stitching, tapering sleeves. In 1963, a “Snob” pinafore dress cost six guineas – the equivalent of just over £100. These were feel-good designs for women – to give them freedom, to enhance their lives.

Mary Quant fits a zip-up mini dress on a model in her design studio in London, 1967. Photograph: Rolls Press/Popperfoto/Getty Images

Having said that, her clothes were not friendly to the curvaceous. “For women who had grown up during the war on a war diet, these clothes worked,” Lister says, possibly stretching a point. She adds that Quant wanted to “flatter personality and loved functionality” (she once said she wished she had invented jeans).

It might seem counter-intuitive to look back at a designer who always focused on the next thing. But the V&A retrospective will show how uncannily contemporary Quant remains – and daring too. Like Peter Pan, her clothes do not grow old.

Lister, asked about her legacy, says: “You wouldn’t bat an eyelid if someone wore Mary Quant now. Her attitude definitely lives on in London’s young designers, keeping London on the map as the centre of irreverent, energetic, street-style inspired fashion. And if you look at the work of young female British designers now, such as Molly Goddard or Simone Rocha, their designs embody the female enterprise and spirit of risk-taking, innovation and fun that was at the heart of Quant’s work.”

This is how Women’s Wear Daily, the American fashion industry’s bible, raved about Quant in her heyday: “These Britishers have a massive onslaught of talent, charm and mint-new ideas. English chic is fiercely NOW.”

With Quant, then and now turn out to mean the same thing.

Mary Quant, sponsored by King’s Road, is at the V&A from 6 April 2019 until 16 February 2020