Maria Grazia Chiuri and Pier Paolo Piccioli's Valentino show was such an alluring conflation of elements it was difficult not to be spirited away and totally enchanted by it. That's when fashion is exciting, when you're so drawn into a vision that your head changes entirely for 10 minutes.

The designers took "stereotypical garments, part of the collective culture," intervened and improved them to perfection, with a nod to 60s British style and Carnaby Street on their strong, youthful casting.

We were taken to a divine world, one where models including #dazedmodelarmy's Alexander Beck stalked their inherited mansion to a noirish soundtrack. Through the Htel Salomon de Rothschild's grand salons, with their ornate painted ceilings, chandeliers and parquet floors, the boys wore transparent soled Chelsea boots, ponyskin trenches, military furs, capes and experimental thermoform tailoring (which moulds a suit to the body), realised in Prince of Wales checks and Black Watch tartans.

We’re all savvy these days. We all know our signs and signifiers, that blue jeans aren’t just blue jeans. Above all garments, they are within each of our grasps, yet continue to represent the most potent aspects of street fashion and sub-cultural style: aspiration, fantasy and drama.

Democratic yet so detailed as to simultaneously appeal to elitist instincts, jeans deliver authenticity, that most alluring of all qualities inherent in objects of sartorial desire.

As embodied by the Levi Strauss 501 - an unimpeachable glory of design and content manufactured in San Francisco from hardy cotton twill from France (de Nmes) for cowboys, gold-rush prospectors, farmhands and railroad workers in the 1860s - denim looks and feels mighty real.

When I put together my book The Look - an investigation into the combustion which occurs when great music meets fantastic visual style - and followed the twisted trail which wound from the utility-wear sold in 1946 by Elvis’s tailors Lansky Bros in Memphis to today’s multi-national, multi-billion and monstrous denim label frenzy, I discovered denim, and in particular blue jeans, at every turn.

The beauty of blue jeans lies as much in the story behind their arrival in the arsenal of popular taste, for it was unplanned, as organic as the fabric from which they are made. I was enlightened to this by the late Malcolm McLaren. As well as being the greatest cultural iconoclast of his generation, he was alsoan astute and educated fashion historian.

For it was at McLaren’s early 70s shop Let It Rock at 430 King’s Road that I first encountered jeans presented not as fashion items but as fetishised totems: the straight-legged Levis were neatly arraigned in single pairs, stiff as boards, the Selvedge seams on display and cards carrying washing instructions proudly foregrounded.

“Look at what the beats, people like Jack Kerouac, were wearing after they left the marines and the army and went on the road,” McLaren advised me long ago. “Blue jeans, white t-shirt, leather jacket. When Hollywood looked around for rebellious images which would suit stars like Marlon Brando and James Dean, they settled on that look. And when kids in Britain saw it up on the big screen, they wanted it to.”

For many years – decades – big business did not understand denim’s desirability, so could not co-opt it. Far from the mainstream in the 50s, Britain’s first menswear boutique, the subterranean Vince Man’s Shop in Soho, sold some of the first home-made denim in light-blue shades to its largely gay clientele (Sean Connery, then a wannabe actor muscleman, posed in a pair in magazine ads) and Marc Bolan, then Mark Feld and one of the UK’s first mods of the early 60s, used to reminisce how there was just one shop in the whole of London – a surplus store in Leman Street, Whitechapel - which stocked original Levi’s originally intended for US service camps around the UK.

“One day we turned up on 40 scooters and stole the lot,” said Marc during his 70s glam heyday. “They were there, one wanted them so one took them. My scooter zipped off without me so I stuck a couple of pairs up my jumper, ran down the road and jumped a bus. My heart was pounding; it was great knowing we were the only ones among a few people in England who had them. That was very funky.”

It was also smart: Modernists such as Bolan prided themselves on The Who manager Pete Meaden’s standard line for his peers: “Clean living through difficult circumstances.” Conversely the art-school graduates who powered the beat boom and British music – the Stones, the Pretty Things, The Kinks – incorporated denims into the scruffy, blues-associating coffee-bar look of Chelsea boots, matelot shirts and pea-coats. That way they could identify with the founding fathers of black music such as Leadbelly, who had been forced to wear denim during his years on the Texas chain gang. One of these young Brits, Peter Golding – who later invented stretch denim in the 70s – even moved to the Beat Hotel in Paris. “I busked on the boulevards and understood the relationship between railroad blues and dungarees,” he once told me.

In the years after the beats, art students and mods, denim was embraced by rockers, Hell’s Angels, skinheads, punks, rockabillies, casuals, hip-hop crews...hell, at the height of Baggy, acid-housers and Cheesy Quavers donned dungarees as the ultimate ant-fashion statement. And in doing so, naturally, effortlessly, in their very British way, they made a fashion statement.

It is here, down the years and in this diversity, that the seriously significant element of any enduring garment comes into play: mutability. At every price point, in different silhouettes and shades, with every conceivable elaboration and variation of detail, denim has multiplied, proliferated and survived.

And so today we crave Fennica x Orslow’s stunning adherence to traditional values and appreciate the recasting of this staple in a contemporary context by the likes of Christopher Shannon[below]and Martine Rose[above].

Denim’s ability to withstand renewed waves of invention, nuance and flair is evident at Pokit, the Wardour Street shop situated just a few hundred yards from where Vince Man Shop traded in flamboyant “Continental-wear” jeans in the 50s.

Pokit’s Seven Foot Cowboy range is the result of Bayode Oduwole’s investigations into the styles worn by rodeo riders down the decades: “We wanted to look at the larger than life characters of the west, the melting pot who made America and the world what it is today,” he says, using an example the side-buttoning Crazyhorse, which have a yoke inspired by those on the seat of Hussar Guard’s britches while the high-waisted shape utilises the roomy design for jeans worn by rodeo clowns, who need maximum mobility to perform their stunts safely.

As worn by Dexys leader Kevin Rowland on the cover to last year’s stand-out album One Day I’m Gonna Fly, the Crazyhorse represents all that is great about denim jeans. I ask you, which other garment could contain circus and military references so comfortably? And which continues to exude toughness and cool in equal measure?