But inspired flamboyance was not his norm. For it would hardly be possible to invent a more traditionally English designer than Paul Smith. Even the name is perfectly prosaic, a reflection of the no-nonsense values instilled in him by a working-class Midlands upbringing. However, he displays that post-industrial English talent for manipulating images, values and ideas, making him a prince of world fashion. But perhaps the essence of his Englishness is the modesty and lack of pretension he has retained while transforming his neat, schoolboy signature into a label now selling in more than 40 countries. "It's just clothes," he says of his metier. "It's not like we're sewing arms back on or anything like that."
In anyone else, such resolute ordinariness might seem the ultimate pose, but with Smith there is no question of his sincerity. His polite, down- to-earth manner has endeared him to a fashion world not noted for its warmth and generosity of feeling. Even the bitchiest stylists, those who dismiss his work as "dull" and "safe", concede he is probably fashion's most amiable designer. Everyone who meets him says "Lovely bloke", along with "Such a nice man". But for Smith, keeping his suede loafers firmly on the ground is as much a business principle as old-fashioned good manners. "I never forget where I came from," he told a French newspaper last year, citing the fact that he learned the trade from his father, who went door-to-door selling linen and clothing to housewives in their native Nottingham.
"It's amazing that Paul Smith has stayed like he has, considering how rich and famous he is," says the writer Hanif Kureishi, a friend who once modelled for him at a Paris catwalk show. "He's really not at all typical of the fashion world."
However, it takes more than modesty to build a name and a fashion empire the size of Paul Smith's. A combination of relentless hard graft, a nose for the next trend, good business practice and the ability to be in the right place at the right time have all played their part in the Smith success story. Having few pretensions seems to have brought him a freedom to roam that few other designers allow themselves. After all, this is the man who changed the underwear of a nation in the 1980s, when he persuaded millions of men to drop their dreary Y-fronts for a pair of floral boxer shorts; who turned an outdated loose-leaf diary system called the Filofax into a status item; who dressed last year's England World Cup team in beige suits (the choice of colour was Glenn Hoddle's - Smith wanted to use a dark blue); a self-made man who sits on Tony Blair's "Creative Industries Taskforce"; whose likeness peers from the walls of the National Portrait Gallery; and who is also the only designer currently enjoying a sales increase in recession-hit Japan. "But then," he explains quickly, "I have been there 45 times."
The Smith name - or in the case of the diffusion range, his initials - can now be found on cutlery, crockery, linen, toothbrushes, sunglasses and stationery. This is as well as the ties, braces, socks, T-shirts, underwear, jeans, shirts, suits - both off-the-peg and bespoke - dresses, skirts, coats, shoes, accessories and other trinkets (like hand-painted cufflinks) that have made him Britain's most successful designer, with a business that puts people like Vivienne Westwood, Rifat Ozbek and Jasper Conran in the shade. It is no exaggeration to describe his company as an international fashion empire: Japan and other parts of Asia account for 80 per cent of his pounds 170m annual turnover, while Europe generates a more modest yet respectable pounds 33m. More importantly, in both markets his sales figures are rising steadily.
The secret of his success? He embodies it. At 6ft 4ins, with no discernible muscle tone, he should look gangly and awkward, and yet he carries himself elegantly and usually wears one of his own slightly quirky suits - perhaps a sharply tailored pinstripe with a purple silk lining and jet beading on the cuffs and lapel - which he will then "mute" by teaming it with a black denim shirt. Likewise, he wears his shoulder-length hair in a ragged and outgrown 70s style, seemingly unperturbed by the strands of silver grey. This is the Paul Smith "classic with a twist" formula, the mantra on which his fortune was founded. The idea is a simple one: take the best of British tailoring skills and fabrics, then add witty design details and eccentric combinations of texture and colour which lift the clothes out of the ordinary - while scrupulously avoiding anything that might resemble an overt fashion statement.
"Looking at the menswear industry today, it's become something of a cliche to talk about `classics with a twist'," says GQ editor Dylan Jones. "But when he pioneered the idea in the early 80s, it was quite radical. It was the first time there had been a marriage between quirky streetwear and the conventional quality of British menswear. I don't think it was even part of a marketing scheme, it was simply how he produced his clothes. And they appealed to that generation of proto-yuppies, who were interested in moving up the social scale and dressing to reflect their new status, but at the same time didn't want to lose their individuality. In that respect, he captured the mood of the times."
Likewise, journalist and broadcaster Tony Parsons says that "though Paul Smith represented the 80s as much as Margaret Thatcher, people who know him know that he never subscribed to that 80s mentality, namely the notion that `money is everything'."
"I like his clothes," says Kureishi again, "because they're simple, easy to wear, and not deliberately wacky like so much fashion." Advertising guru John Hegarty believes that Smith's dry humour is his greatest design asset: "He makes people smile, and that's a quality that's all too rare in such an uptight, self-important business as fashion." Smith himself no longer uses the "classics with a twist" line - overuse has devalued it. Instead, he describes his style as "Savile Row meets Mr Bean".
Paul Smith was born in July 1946, part of that post-war generation that grew up wanting more, yearning for an end to rationing and desperate to shake off the class structure that still shackled their parents. Yet he has never turned his back on his roots and he still identifies closely with his Midlands background. "I'm proud of my origins," he has said, "of being English, provincial and of having connections to the artisans, traditions and humour of the region."
Smith was never going to be an academic. He quit school at 15, a decision that he has since been heard to regret. "I would have loved to go on to further study," he admits, "but I'm not a great reader." ("I don't think he's ever read a book right to the end," laughs Hanif Kureishi.) Instead, he became an errand boy in a Nottingham fabric warehouse. Having developed a keen interest in cycling at the age of 11, he briefly entertained dreams of championships and medals, training seriously enough to clock up 300 miles a week - despite the antipathy of his father, who "never thought it was a real job".
The matter was decided when he was involved in a road accident with a car, which left him with a broken femur, as well as fracturing his nose and several fingers. Emerging from hospital six months later, the aspiring young cyclist found he could no longer bend his leg enough to pedal. "And that's when I discovered the English pub," he says. Fortunately for him, his local was frequented by art-school students - aspiring fashion designers, artists, photographers and architects - who introduced the bright but naive working-class lad to a new world of sophistication.
At 18, he discovered London and the Swinging Sixties. He also met and fell in love with Pauline Denyer, a fashion graduate of the Royal College of Art, who would become his muse, his business associate and his long- term partner (who he refers to as his "wife"). "She's been my key to the world of fashion," Smith has said of his retiring partner. "In fact, she's the key to everything I've ever done. I couldn't have done anything without her." Although Smith is usually happy to indulge his sociable side unescorted, they rarely appear in public as a couple, preferring to shun the media spotlight and entertain at their London home, where they live with Denyer's two children. In fact, he is noticeably defensive concerning his wife and resents the way she is treated whenever they go out as a couple. "It's always Paul Smith this or Paul Smith that, but people never seem to acknowledge Pauline," he told Liberation last year, "even though she's a painter, an intelligent woman. I can't stand the way people behave towards her."
Aged 24, and with pounds 600 to his name, Paul Smith opened his first boutique - in a cramped backstreet stockroom - in his hometown, which was still suffering from a post-war hangover. By this time, Smith had become something of a dandy, wearing pink suits and scarlet snakeskin boots. Some Nottingham residents were obviously not ready for this. "Old men used to come up to me in the street and shout: `Look at you! You look like a woman! You should be put in a dress! I fought in a World War for people like you!' "
With Denyer's encouragement and financial support (she was teaching at art school to support them both), Smith studied fashion at night school. In 1974 he opened his first high-street shop, which still bears the Paul Smith name. In 1976 he decided to show his first minicollection in Paris, with a reggae soundtrack. Three years later he opened his first London boutique, in Covent Garden's Floral Street - a much less desirable address then than it has become. Two decades later, he has colonised an entire stretch of the same street, and his neighbours now include a plethora of trendy boutiques like Nicole Farhi, Agnes B, Jones, Burro and Jigsaw.
Unsurprisingly, perhaps, Paul Smith has now become an international media story; last year, an exhibition of his work, True Brit, travelled around Europe and Asia, often attracting sell-out crowds. In Tokyo, where Smith is even better known than many Japanese designers, more than 20,000 people bought advance tickets as soon as the dates were announced.
Smith's is such a remarkable success story, and his personality so eminently embraceable, that one might wonder why, as yet, he has not been honoured by a Government that has shown itself only too eager to play the populist card. Perhaps memories stretch back to 1992, when he refused the "prestigious" British Designer of The Year award. Smith snubbed the gong, describing it as "self-congratulatory".
"I couldn't see the point of it," said Smith, "because our fashion industry, in terms of design, was so tiny. The awards were just an invention by the PRs to draw attention to Fashion Week. They didn't have any substance, and I don't like to be involved in things that don't have a foundation."
Whether or not there is an OBE waiting for Paul Smith, this coming London Fashion Week can be thankful that a designer of such integrity still graces its calendar.
Born: 5 July 1946, Nottingham.
Family: Father, Harold, a credit-draper. Mother, Marjorie. Long-term partner, Pauline Denyer, a fashion graduate and painter. No children.
Education: Beeston Fields Grammar School. Left at 15.
Career: Opened first shop (part time) in Nottingham in 1970. First `Paul Smith' shop opened in Nottingham in 1974. First Paris catwalk collection, 1976. First London shop, 1979. Shops now also in New York, Paris, Hong Kong, Singapore, Taipei, Manila and Japan.
Recognition: Hon MDes Nottingham Trent, 1991; Paul Smith True Brit exhibition, Design Museum, 1995; Queen's Award for Export, 1995; Freeman, City of Nottingham, 1997.
He says: "We don't give anything to anybody - and we sell to everyone from Oasis through to the Jaggers and Bowies."
Admirers say: "A true Brit. If there were more people like him, Britain would be a greater place." (Terence Conran)
Critics say: Stylists complain privately of "dullness" and "safety" - but few in the British fashion world dare challenge his work in public.