"Extracting oil from tar sands is going to kill babies," Vivienne Westwood says. The emphasis is hers, not mine. Britain's most famous fashion designer then leans forward, her blue eyes bright and serious. "For every pound or kilo or gallon or whatever," she continues, her hand with its unvarnished nails flapping distractedly at her side, "you're going to kill a child."
On Westwood's head is a hat that reads "Chaos," around her neck a scarf that says "Leonard Peltier" (working to free the native American activist, in prison on a murder conviction, has been one of her life's causes).
You may gather from all of this that Westwood cares much less about pin tucks, her role as an architect of punk or who's designing the royal wedding dress - it's not her - than she does about the ruination of the planet or the utter futility of the 20th century. Listening to her is exhausting and exhilarating, like sitting with a beloved but slightly barmy aunt who has read the collected works of James Lovelock over the Christmas holiday and plans to give your ear a right old bending.
We are sitting in the light-filled restaurant of one her favourite places in London, the Wallace Collection, a dazzling museum of 17th- and 18th-century art that contains masterpieces such as Fragonard's The Swing and Hals's The Laughing Cavalier. Strangely, the museum isn't on the regular tourist trail, which is one of the reasons it's included in Vivienne Westwood's London, a very personal documentary that airs on CTV Saturday night.
The film is Westwood's attempt to drag visitors away from the tired round of Buckingham Palace-Big Ben-Madame Tussauds and into London's hidden nooks and crannies, one of which is the Wallace. "She's not wearing any knickers," she says in the film, pointing to the smiling minx in The Swing. "That's the joke." It is a joke much appreciated by the 69-year-old designer, who famously showed up at Buckingham Palace in 1992 to collect her OBE without benefit of underwear. (She was made a Dame four years ago.)
Wheeling around London on her bicycle like an avant-garde Pippi Longstocking, Westwood stops at the Barbican concert hall, Brixton Market, the National Gallery. She is on a mission to instill culture in a legion of snow-globe-buying Philistines, because she believes, with deadly earnestness, that a lack of cultural appreciation is what's dooming our planet.
"If you're an art lover, you're also a freedom fighter, and you need to take part in trying to save the world," she says, pulling her Chaos hat down more firmly over her flaming orange hair. Not modern art, mind you, which she believes is ... well ... "crap" wouldn't be too strong a word. "The 20th century was a mistake," she says. "There was nothing produced in the 20th century, no ideas. There's not one person alive who could paint one flower on that porcelain" - again, the hand flutters toward the Wallace galleries - "or anything that's in there."
How odd to hear one of the architects of punk venerating the past. She and her partner, the late Malcolm McLaren, sold bondage trousers and rubber fetish gear out of Sex, their Chelsea shop. They also discovered a sullen young rascal called John Lydon, who one day added Rotten to his name, making history. Actually, it's a bit radical, this rejection of the present and the future. A bit punk.
"It's true," Westwood admits. "I was against the Establishment and, in those days, associated the Establishment with anything from the past. But I changed my mind." She says this with the blithe certainty of someone who doesn't care about currying favour or indeed making a lot of linear sense. If anything, it's her particularly English eccentricity that has made Westwood such a well-loved figure. Her contradictions are what people love. She is the author of an anti-consumerist manifesto called Active Resistance to Propaganda, but sells clothes and accessories that only the rich can afford. ("Buy less, choose well and make it last," she says in response to any criticism.)
Westwood doesn't have a mobile phone, and pulls the television cord out of the wall when she arrives at a hotel. She is not, to put it mildly, a fan of popular culture: The first Sex and the City film brought her a new level of international fame, when Sarah Jessica Parker as Carrie Bradshaw decided on a beautifully sculpted Westwood dress for her wedding to the undeserving Mr. Big. Did she like the film?
"I don't like any movies," she says with a shrug. "I don't like going to the cinema." And she hasn't been asked to design the other wedding dress that's on everyone's mind - the one that Kate Middleton will wear this spring at Westminster Abbey - although she does have an anarchic suggestion for the future princess: "Maybe she should get it from Topshop. But she's not getting it from me."
She says this in a wonderfully sing-song lilt that still echoes from the Pennines, the high hills in northern England where she grew up. Half a century in London, where she once worked as a primary-school teacher and raised two sons, has barely softened her accent.
There's a bluntness about Westwood that, in England, is associated with people from the North. She's known throughout the world for designing clothes that are beautifully cut and draped and look particularly lovely on women-shaped women, but it's not a job she desired or even enjoyed very much.
"I didn't want to be a designer," she says, "and I didn't like it for at least 15 years. It sounds a bit pathetic, but I did it as a duty, because I knew I was so good at it. I also thought it might help me to understand the world. Then one day my husband [Andreas Kronthaler]said to me, 'You have to like this job,' so I thought, well, I will."
As rain begins to fall on the restaurant's skylights, Westwood wants to turn the discussion to a subject she actually cares about: climate change. "It's an absolute crime that Canada's discussing who owns the Arctic," she scolds with such schoolmarmish vigour that I want to assure her I'll write a letter to the Prime Minister as soon as I get home. But first I'd like to extract one piece of advice for tourists about what to avoid in London. "What to avoid?" she says, sounding puzzled. After a bit of a think, she says, "Don't buy anything. Whatever you do, don't buy an 'I love London' T-shirt. I've got one that says 'I love crap' instead."
CUTLINE: Dame Vivienne Westwood takes in the art at the Wallace Collection, one of her favourite London museums. JONATHAN WORTH FOR THE GLOBE AND MAILReport Typo/Error