It was all in the name of fighting climate change, the onetime punk priestess' favourite cause.
Westwood turned her London Fashion Week show into a soapbox, using two models to unfurl a banner proclaiming a climate revolution, then strutting down the aisle to call attention to the need for change.
Westwood, with a devoted fan base going back four decades, was greeted with thunderous applause, in part out of adoration for her unique personality and in part out of appreciation for a show that somehow made a bizarre combination of late 50s and early 60s looks seem at once glamorous and tongue-in-cheek.
"I loved it," said former model Jo Wood. "There was so much there that I wanted. And I love Vivienne as a person. She's the one show I won't miss. She always does what she believes in, and we should all be organic."
The show itself was unusual, with many of the models sporting distinctive makeup that gave their faces green, pink or lavender glows.
This contrasted sharply with some severe outfits dating from just before the "Mad Men" era, when First Lady Mamie Eisenhower helped set conservative fashion trends.
Some outfits looked silly, others — evoking the Jackie Kennedy era that came a few years later — appeared wonderfully retro and chic.
Success or failure? Westwood said she couldn't care less.
In an interview before the show, Westwood said she has no interest in fashion and only uses it as a way to focus attention on the danger posed by climate change, which she predicted could cause humanity's extinction within a single generation.
"I'm not going to discuss the collection," she said of her Red Label presentation, which traditionally mines her extensive archives for ideas that can be freshened and renovated.
"I can't talk about fashion. I'm too preoccupied with using it as a vehicle for talking about climate change, which is an incredible danger. Everybody who's eco-conscious is fighting the revolution and of course we need to get more people involved, to pressure the governments, to sort this out, because we have to sort this out."
Still, Westwood said she remains an active fashion designer and has not given up her job.
But she advised women to buy fewer clothes — going as far as saying they should skip the items in her new collection — in order to reduce waste.
Westwood also expressed sympathy for Prince William and his wife, the former Kate Middleton, over topless photos published in France and elsewhere in recent days.
"They have to protect their privacy somehow because if they don't do it now it's a total free-for-all," said Westwood, who boasted about not wearing underwear when she received a medal from Queen Elizabeth II.