Hollywood also reveres her, including A-list fashionista Sarah Jessica Parker, who wore her wedding dress in the much-publicised Sex and the City. Unimpressed, Westwood walked out of the premiere after 10 minutes, declaring the film uninspiring on the fashion front, and 'quite dull'.

Her private life is equally non-conformist. Andreas Kronthaler - her third husband, and creative director - is 25 years her junior, while she declares sex 'overrated'. They met when he was a mere design pup - she was his teacher - and they've been happily married for almost two decades.

Westwood has long been a loud spokesperson for the environment. When she was invited to redesign the BRIT Awards statue, unveiled in January, she replaced Britannia's trident and shield with a Union Jack-draped toga dress, showing off her feminine curves and redefining her as leading the fight against climate change.

She advises young women to wear ribbons of torn cloth as bikinis, pin pictures of boyfriends to their sleeves, dig out old clothes from their mothers and repair clothes instead of buying new ones.

'I say there is status in holes, especially as you patch them, because it means that you've chosen something and you really like it and it's part of your personality,' says Westwood. 'I think it's what things should be about, not everybody looking like everybody else. Not buying all these landfill clothes that are made by people on less than a dollar a day.'

Other personal energy-saving tips include rarely washing her clothes, using talc as deodorant and avoiding flushing the toilet. Kronthaler has compared her to a monk, saying she lived for 30 years in a tiny council flat, and that when he finally convinced her to move into a house, she had no belongings to bring whatsoever.

While most global brands are scrambling to keep up with the rapidly changing times, Westwood scoffs at the idea of 'forward thinking'.

'I know that if I'm happy with something, someone else will want to wear it,' she says. 'I cannot predict what people will be wearing in the next decade - I tend not to follow fashion trends as such.'

It's the past and the present, she explains, that give us perspective. 'People are so busy keeping up with the times that they miss everything for the sake of wanting to know what is coming next,' she says. 'In order for our imagination to function, we should try to understand what human beings have achieved in the past and compare it with nowadays. Then we may see the connection between cause and effect and glean what the future might be.'

Westwood's style has evolved numerous times since in 1971, when she and her late husband, Sex Pistols manager Malcolm McLaren, opened a shop on London's legendary King's Road. Known today as World's End, the shop was then called Let it Rock, and sold rock and roll clothing at a time when hippies were in fashion.

By 1974, they'd tired of the Teddy Boys who bought their clothes, and renamed the shop Sex, filling the shelves with bondage gear, rubberwear for the office, provocative T-shirts with zips, holes and pornographic slogans. Westwood and McLaren were pushing punk into the mainstream, and redefining street culture while they were at it.

Since then, Westwood has gone from punk to pirates, pirates to pagans, and by the end of the decade was studying Savile Row tailoring techniques, and channelling Victorian sex appeal.

Today she retains her appetite for historical influences, and for this spring-summer, sent models down the catwalks with teetering messy beehives, beauty spots and her signature painted-on eyebrows. There was also a marked recycling theme to the collection, the first look resembling a sort of gorgeous burgundy silk couture rubbish bag.

Meanwhile, Westwood's proudly independent global empire continues to expand. Asian consumers, probably drawn by her non-conformist spirit, love her clothes. She opened her first flagship in Hong Kong in 2002, and today her 12 boutiques here are a favourite among local celebrities such as Faye Wong, Wyman Wong and Charlene Choi. But her biggest market in the region by far remains Japan, where fans flock to her 45 shops and 117 department store counters.

Now, she's returning her gaze to youth - she was once a primary school teacher - and uses the internet as a platform to educate them. In November she launched the Get a Life website (activeresistance.co.uk) and a blog to promote her manifesto, Active Resistance to Propaganda.

'Non-stop distraction makes people gullible,' reads the manifesto, which urges young people to embrace art and culture.

'I believe the art lover is a freedom fighter for a better world - today and in the future,' writes Westwood on her website. 'We need more young art lovers to help save our beautiful planet.'

Four decades have passed and they're still listening to her.