Karl Lagerfeld doesn’t like to talk about the past. He refuses to discuss his 50-year career with Fendi, for whom he was made creative director, in charge of fur and women’s ready-to-wear, in 1965. Neither will he dwell on his 32-year stewardship ofChanel, where he has been the chief designer since 1983. He hasn’t even been to visit his vast “futurespective” in Bonn, Germany, the most complete exhibition of his oeuvre ever mounted, featuring everything from a reproduction of the coat for which he was awarded the Woolmark prize for design in 1954, to his first collections for Chloé (for whom he worked between 1964 and 1996), and from a regiment of mannequins dressed in Chanel tweeds, through Fendi furs to pieces from his own eponymous line.

Absolutely not! For Lagerfeld, nostalgia is a creative poison. “I’m very much against it,” he says from his studio in Paris. “I’m always into the next step. I’m interested in what’s going on, not what has happened. I never look at the archives. I hate archives!”

If Lagerfeld sounds impatient, he is. His career has been built on a light-speed forward momentum. It’s the same urgent energy that has enabled him to juggle the demands of three entirely separate and visually distinct houses at the same time (Fendi, Chanel and Karl Lagerfeld) and maintain alternative occupations as a photographer, occasional writer and keeper of Choupette, a snow white cat he was given in 2011 and who now commands an Instagram following of 64,000 followers. Even his unique German accent sounds impatient; like a man exasperated by a sentence’s formulation in his mouth.

His brisk focus brushes aside those things that displease him. He has already dismissed a publicist from our three-way phone conversation: “I don’t like it when someone listens when I talk to someone.” He also forgoes deep analysis of his creative ideas: “I don’t put that into words because then it would become marketing.” And too much talk of global trends is met with the immaculate: “You know, I’m not in the sales department.”

To begin with, he’s not too happy to talk about Fendi’s upcoming couture show either, which is a shame because that’s what we’re supposed to be doing. Fendi’s first foray on to the couture stage, next week’s Haute Fourrure (high fur) collection, is a debut for the house and the second of two couture shows that Lagerfeld will stage in Paris next week. (In fact, pedants could argue, it will be the third, as he will present Chanel couture twice so as to accommodate everyone who wants to see it). Mounting two collections, within as many days, which serve two different masters, is a superhuman undertaking, especially considering the designer is now 81, or thereabouts (discussion of Lagerfeld’s exact age is hotly discouraged).

“It was their idea,” he says, when I ask about the Fendi show’s genesis. “I thought it was interesting because there’s the market for that [couture], so I thought it could not be a bad idea to show the top of the craftsmanship in that business. But I didn’t propose to do two collections at couture. I have more jobs and more work than I need...”

For the inaugural show on Wednesday, Lagerfeld will deliver about 30 looks in a collection that will shine a renewed focus on the brand’s heritage as a specialist fur house and clothing line. The Italian luxury house was founded as a fur and leather brand by Edoardo and Adele Fendi in 1925. The couple then passed on the reins to their five daughters and, today, granddaughter Silvia Venturini Fendi oversees the men’s and accessories lines alongside Lagerfeld (it was she who introduced the cult “Baguette” handbag in 1997). The house still manifests as a family business, even though LVMH bought a majority stake in 2001 and has since installed a chief executive, Pietro Beccari, who has been instrumental in creating a vision for the brand.

For Fendi, already fabled for its novel treatment in a highly technical field, Haute Fourrure will be the ultimate expression of “fantasy fur”, as represented by the house’s double “f” logo. Fendi has always innovated with its manufacturing methods: In 1989 the house developed a “grained leather” technique, that combined fur and leather to create a lighter take of the traditional brown coat. More recently, Lagerfeld has played with texture: for SS15, he used shaved mink, inlaid with vivid geometric designs, to create a “fur that doesn’t even look like fur”. Meanwhile, the house’s “bugs” — neon-bright clip-on handbag accessories with cartoon faces that retail for about 500 a piece — have become an essential feature of the street-style uniform.

The couture show will allow him to experiment even further. “Typically, the old furs hardly exist any more,” he says of the heavier material that he used to work with. “So it’s all in the craftsmanship. And at this level, you can push it to a level of craftsmanship that would be too expensive for ready-to-wear: mixing things, design, pattern, fur mixed with feathers, all kinds of things. For me, this is what’s interesting.”

To put a dedicated fur show within the couture schedule is not without controversy. But Lagerfeld doesn’t do much soul-searching over the use of this most morally complex material. “It’s changed since in the 1990s and that’s a good thing,” he says of the legislation that has seen the industry become more rigorously regulated. Nevertheless, there will always be people who see fur as wrong. Lagerfeld, who doesn’t wear fur himself, says. “As long as people eat meat and wear leather...I don’t see the thing...” he sighs. “It’s a little too easy, you know — there are enough unemployed people in the world that you cannot suppress a whole industry that would have nothing else to do.” Besides, he adds: “The sales are good.”

The sales are indeed good. According to Mark Oaten, chief executive of the International Fur Federation, the global mink industry alone is worth 3.7bn, while fox fur is worth a further 880m. Even in the UK, one of the most squeamish nations when it comes to the subject (and where exotic fur is not featured in many British fashion monthlies) the sales figures are steadily increasingly. “We saw a 20 per cent rise in London last year,” says Oaten. “And we don’t think this was all down to tourism. Sales in cities like Manchester and Leeds are also seeing an increase.”

Only time will tell if Fourrure is a commercial success, but placing the house on this rarefied stage is a neat bit of brand extension, all part of Beccari’s desire “to promote and promote and promote,” according to Lagerfeld. The house will hope also to lure a small but significant clientele, whose numbers have been swelled by the new markets in Russia, Asia and the Middle East.

“Couture is doing very well” says Lagerfeld. “I have no idea how it works at other houses but at Chanel, it’s kind of a miracle.” Why does he think that is? “People want something that is worth spending their money on. “Today, very basic classic things don’t sell, or they have to be in a new material. They have to be from a new world.”

Many creative directors describe couture as being a crucible, in the sense that it allows them to distil a vision that will ultimately inform all of their ready-to-wear. No surprise, Lagerfeld is appalled by the notion.

“It’s a completely different spirit,” he says. “If it was in the same spirit, I just wouldn’t do it because I would be bored to death. I would just say no. No, no, no!” For him, couture is about “the craftsmanship, the proportions. It has nothing to do with the ready-to-wear. It should not have anything to do with ready-to-wear.”

Instead, Lagerfeld starts every collection in the same way. With a blank piece of paper and a pencil. “I sketch things, because I sketch everything,” he says. “I don’t work with artists. I sketch everything myself. I wanted to be an illustrator and a potter before I was in fashion, and I was in fashion nearly by accident. So when I do a sketch that I keep — because 99 per cent goes to the garbage can — it is hardly changed. And the collection is made in exactly the way I made the sketch. Look at the boards, at Fendi and Chanel. You’ll see the sketch and you’ll see the final dress and they are the same. I’m not there draping for hours and asking myself a hundred questions. Those questions I ask myself before I draw the sketch.”

Lagerfeld’s process, then, is to “propose” the final garment and then task others with conjuring it to his satisfaction. “Exactly, exactly. But I like to see it done in material, in another dimension. It’s very exciting and very interesting. Sometimes you’re disappointed, sometimes you are not. It’s a very strange job. But that’s what I like about it.”

If Lagerfeld likes to play with new manufacturing techniques, it’s because his sketches challenge the limits of what can be done. Only here does he admit to the advantage of a career’s worth of experience. “For once, I must say, I have done it for such a long time that, for me, they can do things that are supposed to be unexpected or impossible.”

Music is playing in the background: it’s a song Lagerfeld can’t identify, part of an ever updating playlist he absorbs to keep abreast of cultural developments. He loves the act of discovery, be it a person, place, artist or book. It was he who first took the fashion show on the road, staging Chanel’s Métiers d’Art (the pre-fall collection) in a unique location every year, and inspiring a dozen other houses to do likewise. He was one of the first people to possess an iPod (he once told journalists he owned 300), and he’s very proud of his new Apple Watch: a bespoke version that was made in rose gold with a matching bracelet. “I think I’m the only one who has one entirely in gold,” he says. “It’s very, very beautiful.”

He’ll never iDesign though. “I don’t design on computers,” he says. “It’s not that I don’t know how; I don’t like it.” He pauses. “You know, I think I’m the last designer that really sketches illustrations. And the people I work with are used to reading my sketches. And sometimes I see a fitting that is exactly what I wanted.”

For a man who bestrides the fashion landscape so completely, the hand-drawn sketch seems also an excellent way of retaining creative control.

“Exactly! exactly!” he concludes. “Whatever that means, that’s what it is, my dear.”