There's no such thing as a constant in fashion, in an industry obsessed with innovation and the Next Big Thing.
But there comes a time in every trend cycle for looking fondly over one's shoulder and learning from one's predecessors, and a new exhibition in London sees a group of internationally renowned designers making a fuss of that most humble fabric, wool.
Wool Modern, which opens on Wednesday at La Galleria on Pall Mall, is part of Wool Week, which begins today across the country; it will run for the month of September as part of The Campaign for Wool, a charity initiative to resurrect the fortunes of the fabric, with one eye on its rich heritage and another on its potential for future sustainability. The exhibition features creations loaned by a host of names, including Burberry, Alexander McQueen, Maison Martin Margiela and John Galliano.
"In these days when we're threatened by encroaching climate change, wool is a very sustainable fabric," says Vivienne Westwood, who has worked in the medium for much of her career and loaned several pieces to the show. "People will not want man-made fibres any more and luxury will be seen in the great, traditional natural fibres."
Indeed, the use of wool and its evolution in Westwood's work rather mirrors its status within fashions past and present. Although she began by ironising its usage in British military uniforms and as a status marker with her punk-influenced and 18th-century-inspired collections that featured strung-out Harris Tweed suits and resurrected English twinsets, Westwood currently promotes its use as part of her ongoing fight against global warming. The fabric's popularity has been dimmed by a reputation for fustiness and the poor-quality knitwear thrown up by the fast-fashion movement, but the industry's favourite dame is a devout proponent of its qualities.
"When I grew up and had two children," she remembers, "my youngest kept having tummy-aches and wouldn't go to school. My mum said to me, 'Buy him a wool vest!' and we never had any problems after that."
The patron of the exhibition is keen environmentalist the Prince of Wales, who may take a dim view of Westwood's iconoclasm but nevertheless has an interest in the environmental potential of a revival of the use of wool. The Campaign for Wool itself aims to promote awareness of wool-making and -weaving as part of British industry, as well as a means of cutting down on the rampant consumerism that threatens to overwhelm our wardrobes.
As well as praising the durability and resilience of wool, a single fibre of which can be bent and reshaped more than 20,000 times without breaking, Wool Modern also celebrates the ingenuity and expertise of the designers involved. From a beautifully printed wool carpet by Erdem Moralioglu for Brintons to an installation of 180 miles of strands suspended like ethereal cobwebs from the entrance hall ceiling by artist Angela Wright, the show aims to defy expectations. And then, of course, there are the clothes – and there isn't a moth-eaten old jumper in sight.
A 1965 haute couture wedding dress by Yves Saint Laurent in white-cream wool and silk ribbons; a diamond-patterned bodysuit from a 1993 Thierry Mugler collection; the steel fluted body-con dress that propelled David Koma to fame when Beyoncé wore it to an awards ceremony. Each shows in its own ways the possibilities of design in the medium, and charts the modernising that knitwear has undergone over the past century.
"Using wool is an essential element in putting my collection together," explains Giles Deacon, whose bullet-shaped black cocoon appears in the show. "I like to use it in as diverse and creative a way as possible – Pac-Man hand-knitted jumpers, giant roving wool scarves to heavy wool cocoons, as well as traditional suiting."
There's also a history available to visitors, charting the commercialisation of wool from early cottage industry via mass production to the luxurious artisanal techniques used currently by many high-end labels. Archive shots recall ladylike wool skirt suits by Pierre Balmain, the infamous Sixties trapezium dresses of André Courrèges and the opulent stylings of Karl Lagerfeld's tenancy at French house Chloé, while a new generation of designers explain the ways in which they have developed their aesthetics through the use of wool.
"Merino is my favourite yarn to work with," says Mark Fast, whose elaborately fringed and cutaway neo-flapper dresses have propelled him to the forefront of fashion – not least because he has shown off their stretch and structure on plus-size models in many of his shows. Every piece is designed by hand on a domestic knitting machine and then fitted carefully to the body. "Many other yarns snap or just don't connect with my machines, but Merino wool knits effortlessly and is of such great quality. It's also easy to experiment with and gives my elastomeric designs a warm lift."
Merino is having something of a fashion moment among yarns, it seems, having been recently added to plenty of sportswear too. The Australian-farmed wool came originally from Spanish sheep taken there by settlers in the 18th century, whose fine coats have since been further refined by breeding, and whose yarn is now used in some of the softest fine knitwear available. It also has the magical properties of keeping warm skin cool and vice versa, and is completely biodegradable.
Beyond the opulence and beauty of the pieces in this exhibition is a central ethical message, and it's only one part of many events and activities across the country during the five-year-long campaign. Other initiatives include the formation of knitting groups which will hold classes in order that novices might try their hand; there are several cities that will see herds of sheep being driven through their centres, too, just in case we'd forgotten wool's provenance. And many more retailers, such as Marks & Spencer, Liberty, Harvey Nichols and Jigsaw, will celebrate the campaign in their stores and in their collections, with window displays to tempt shoppers in, and heritage fabrics taking pride of place. There are plans, too, to export Wool Week across the globe: a sheep field will be installed in one of New York's main shopping streets, while fashion students in Amsterdam will also be enlisted to the cause.
"Wool is incredibly versatile," Vivienne Westwood adds. "What I delight in is how it has been used for all the uniforms of the British Empire – hunting foxes, going to the North Pole, opening Parliament, going to school."
While the Empire might have crumbled, it's clear that Britain still has some exports that the rest of the world pays attention to: our fashion designers, of course, and wool, their most precious ingredient.
Wool Modern opens on Wednesday at La Galleria and runs until the end of the month; see www.lagalleria.org