She's the queen of modern French dressing, so an Isabel Marant for H&M collaboration was always going to get fashion pulses racing. The Guardian fashion desk pick their favourites

With a lineup that references 90s minimalism and Isabel Marant, M&S is about to unveil its most fashion-led look for years. Will it turn the store's fortunes around?

A "hero piece" is a fashion term for the one seasonal item that can pull your wardrobe out of the doldrums. This is usually hyperbole – except, perhaps, in the case of Marks & Spencer.

Last week, when M&S released disappointing results showing a fall of 1.3% in sales between July and September compared with the same period last year, bosses were quick to point out that the first fashion range to be masterminded by ex-Jaeger boss Belinda Earl was only on sale for the last three weeks of that period.

In other words, the famous £85 pink coat, the breakout star of the M&S autumn collection, may yet save Marc Bolland's bacon.

Earl's second collection, unveiled to the press this week and scheduled to "drop" from January, makes it clear that M&S is pinning its hopes on fashion more than ever. Influences from the catwalk are stronger than they have been in years. A silk bomber jacket emblazoned with Japanese-style herons looks like a nod to the Jonathan Saunders bombers that flew straight from his London fashion week show to every fashionable wish-list. And – canny, this, because fashion's lines of succession no longer run only from catwalk to high street – the high profile of Isabel Marant, thanks to the hype around the H&M diffusion line, is represented by a shrug-on, paisley-print casual jacket (£59), which nods to the £199 beaded jacket in the about-to-launch H&M Isabel Marant collection– a smart move,  since only a tiny proportion of shoppers will get their hands on the H&M Marant pieces they want.

Meanwhile, a voluminous, quilted, drop-waisted, sleeveless dress seems to echo the "cloud" dress that Victoria Beckham made the best-known piece in her diffusion collection, when she wore it herself, hot off her New York catwalk. (Differences include the neckline, and the £45 M&S pricetag.)

The M&S customer wants fashion. When Earl showed her first collection in May, she was keen to focus on the upgrade in manufacturing quality and shopping experience – but press and consumers picked up, instead, on the Céline-esque pink coats and the JW Anderson-ish windowpane checks.

"Our customer wants fashion, and it is important that we show that we are confident in our expression of fashion," says Earl. "We need to demonstrate to her that we at M&S are part of fashion." One of Earl's shopfloor changes has been to introduce more dressed mannequins, to break up the racks of clothing and suggest outfit ideas. "They have been incredibly successful," says head of design Neil Hendy. "We keep having to re-style them, because whatever we put on the mannequins sells out." The M&S Christmas advert has a notably high fashion content this year – the standout line, after all, is Helena Bonham Carter complimenting Rosie Huntington-Whiteley on her shoes.

As it happens, next spring is a tricky season in which to depend on catwalk trends to get cash tills ringing. The fashion shows did not produce many trends that lend themselves to an easy sell. Many of the trends are abstract and intellectual. A vogue for "avant blande" and deliberate understatement; a revival of 90s minimalism; a craze for prints inspired by street or abstract art – none of these are box-office gold in the way that, say, "50s sex kitten" or "power dressing in pastels" would be. But Earl and her team have made a clear decision to back fashion rather than fall back on "timeless classics".

The most prominent colour on the M&S shopfloor next season will be white. Usually thought of as impractical and unflattering, it is a bold choice for a brand that must dress women of all shapes and sizes – and whose customers have high expectations of longevity and durability from their purchases. A long-line pencil skirt with a woven texture has a high waistline, so that it can be worn with a matching waist-length sweater to make a modern two-piece suit. The too-cool-for-school 90s minimalism look is also surprisingly strongly represented, in lean cutaway dungarees, several covetable sleeveless jackets and lightweight parkas, and a spaghetti-strap silver slip dress that resembles the Liza Bruce one worn famously bra-less and with black knickers by a young Kate Moss back in 1994.

But, just in case fashion proves not to be the knight in shining armour of the M&S story after all, Earl has a Plan B up her sleeve. A recurring theme of the collection is the summer coat. There is a notch-lapel version in mint, a subtle echo of that famous pink; an oversized lightweight grey tweed jacket; a smart lemon-yellow duster; and a British-made white trench. One of these is likely to appeal to every customer, at some point next spring. When all else fails, you can always rely on the unreliability of the British weather.

Purple is not just for elderly eccentrics. Jess Cartner-Morley selects some purple clothes for your wardrobe

Call me old-fashioned, but a fashion show without clothes is not my kind of fashion show. And I know what you're thinking, but it's not like the lingerie brand's show is about sex either

It is the most expensive catwalk show ever staged, but it has almost nothing to do with fashion. They're not really into irony at Victoria's Secret, so the joke gets a little lost in the dazzle of white teeth and diamond-encrusted bras and paparazzi cameras, but it's quite funny, when you think about it.

All the signifiers of a fashion show are in place when Victoria's Secret stages its annual extravaganza. The model line-up always includes high-end Paris fashion week names (Cara Delevingne and Jourdan Dunn have featured in recent years) and the show is styled by Sophia Neophitou, who as stylist and collaborator to Roland Mouret and Antonio Berardi and British Fashion Council ambassador is an undisputed powerhouse of high fashion taste. The 6in high heels are designed for the occasion by Nicholas Kirkwood, the talented young shoe designer who was just snapped up by LVMH.

But there's something missing. Call me old-fashioned, but I sort of think the absence of clothes is a dealbreaker as far as fashion goes. At the Victoria's Secret show, instead of clothes, the models wear underwear and massive fluffy angel wings. I've been a fashion editor for 15 years, I've seen all kinds of crazy accessories anointed a fashion must-have, but massive fluffy angel wings? Nope. Not a catwalk trend. Never.

I know what you're thinking: it's about sex, stupid. Well, here's the thing: I don't see that Victoria's Secret is really about sex, either. The presentation of the Victoria's Secret Angels, to give the catwalk models their faintly creepy official title is look-but-don't-touch in the extreme. Like a very grand ballgown, or a bridal dress with a train, the wings form a kind of exclusion zone, making it physically difficult to get close. Also, even if you did find a woman dressed in an oversized Angel Gabriel costume sexy, which seems a little dubious, you'd have difficulty getting intimately acquainted. The wings Alessandra Ambrosia wore in the 2011 show were gold-plated antique copper decorated with 105,000 Swarovski crystals. They weighed almost 10kg. There is as much neon, crystal, and metallic on the VS runway as there is satin and maribou. The VS catwalk cipher might be look-at-me, but it's hard to argue that it is come-and-get-me. The name Victoria's Secret was chosen, in 1977, to set a mood-music of sobriety and respectability, and that wholesomeness is still there, despite the acres of flesh on show.

When you visit the store, you notice how little of the product is sexy in the sense of being designed for sex. Much of the shopfloor is dominated by bras bulked up by gel or foam padding. In these, a woman may send a sexual signal when dressed, but she will need to undress alone. The vast "Pink" sub-brand of pyjamas, sweatshirts and logoed vests sells an aesthetic of the tween sleepover, not booty call. But there is no doubt it works: last year, sales at Victoria's Secret totalled almost £4bn.

The VS brand has very little to do with actual sex, and everything to do with sexiness as a status symbol. The brand has as much to do with women looking at other women, as it does with men looking at women: for every 17-year-old boy ogling the model's arses, there is a 16-year-old girl staring at their abs. VS deliberately emphasises the intense competition amongst models to appear on the catwalk; among the most "liked" posts of the endless Instagram photos of Angels-in-training are those which feature the models in boxing gloves, punching their way to a catwalk turn that could earn them a seven figure paycheque.

The Victoria's Secret show takes the cheerleader tradition, and removes the boring old football game. Sportsmanship is old hat; the 21st century is all about being hot. This is the Superbowl, for those gifted with lovely hair, beautiful bottoms and superhuman endurance for juice fasting. These days you can be a champion – an Angel, a higher being – just by being sexy. That's a trend, for sure. But it's got nothing to do with fashion, so don't blame us.

Second Design Museum homage to veteran British designer focuses not on trademark designs but all aspects of the business

"If you ask a question, I'll give you a pair of socks," announced Sir Paul Smith at the press conference to launch a new exhibition about his life, work and creative process at the Design Museum in London.

And with that, the stiffness in the room was punctured, and reporters jostled for the chance to shout their queries, and in return be lobbed a pair of stripey socks from the front of the room, by the fashion designer.

Smith, whose suits are worn by everyone from David Cameron to Tinie Tempah, Sir Mervyn King to David Beckham, has built a business with an annual turnover of £200m by making people smile. "What he does is create a pleasant experience out of very ordinary things," says Donna Loveday, the exhibition's curator. The Paul Smith brand has captured a combination of lighthearted wit, sophistication and British tradition which succeeds in turning cufflinks, wallets, socks, shirts and ties – the everyday essentials of the British man – into fun and desirable purchases.

Hello My Name Is Paul Smith is a second Design Museum exhibition for Sir Paul Smith. In 1995, the True Brit show marked 25 years of his company; in the 18 years since then his empire has continued to expand, making Smith the most consistently successful fashion designer in Britain and the only one to combine commercial success with critical credibility. A company which began in 1970 with one shop, now has more than 300 stores worldwide.

"Classics with a twist" is a dearly held Paul Smith motto, and the twist in this exhibition is that in an era when fashion exhibitions are increasingly in vogue, this one is not really about fashion at all. Clothes on mannequins play second fiddle to displays celebrating the creative process and the history of Smith's business. This is a deliberate move, intended to convey a message: that creativity and hard work are what matter, rather than money or glory.

"This exhibition is not just about fashion, it's about how Paul sees the world," says Deyan Sudjic, director of the museum. A film made on the day of Smith's most recent Paris menswear show puts the catwalk glamour within business, sales and marketing.

The exhibition includes a theatrical set remake of the Paris hotel room in which Smith showed his first collection to buyers, in 1976. Hiding his own suitcase and personal effects in the bathroom, Smith hung his wares in the wardrobe, and laid out shirts on the bed. But no one came - until 4pm on the last of the four days, when one buyer arrived, and placed an order. "That was what got me started," recalls Smith. "I want to encourage young people and to send a message that from a small beginning you can make progress. It doesn't have to be overnight. Young designers come to me now and they think they need catwalk shows, they need 20 shops straight away. But there was no great turning point in my career, no one moment when I suddenly became famous. It's important to be patient, to be humble, and to enjoy every day. This morning I went for a swim at 5.15am, and was in my office at 6am. The first thing I do in my office is put some vinyl on – today it was Talking Heads – and then I start work."

According to Design Museum staff, when Smith arrived for his press conference, he immediately began tidying the stock in the pop-up shop adjacent to the gallery. "I'm a shopkeeper at heart," he told them.

"Our first meeting about the exhibition took place in Paul's office, surrounded by cameras and bikes and books and toy rabbits and letters, and as we talked it became clear that we needed to recreate this room in the exhibition," says Loveday. The two largest spaces are devoted to displaying a tiny fraction of Smith's personal collection of art and mementos, and to a reproduction of his office, with art tomes, bolts of fabric and postcards from fans. By placing his fashion archive in a supporting role to his workplace and sources of inspiration, the 67-year-old designer makes it clear it is the ongoing creative process which interests him, rather than his legacy. "This is absolutely not a retrospective," he told reporters. "And as for retiring – I don't understand that word."

'The Obamas have rebooted purple by making it modern'

With all due respect to the Vatican and the royal families of Europe, the Obama White House pretty well owns purple. At Barack's inauguration at the beginning of this year, Sasha wore a pinkish-purple coat, Malia a violet one, and Michelle aubergine J Crew gloves with her navy coat. Back in 2008, Michelle wore a purple dress in what was to become one of the best-known images of that election campaign: the Obama fist bump. (Purple shift dress, tooled black leather belt, outsize pearls, those arms. Remember?) Purple is the grandest of colours, but for the most part untainted by political association in the way that, say, red is. It is powerful and ceremonial, but graceful and nonpartisan.

Now the Obamas have rebooted purple by making it modern. In the pre-Obama era, purple was nailed by the Jenny Jones poem Warning: "When I am an old woman, I shall wear purple." It was a colour that an essentially mild person would consider daring, which is a different thing entirely from being a colour of genuine rebellion and daring. The Obamas, with their knack for making the ceremonial photo op look unstuffy, have breathed new life into the colour. Samantha Cameron and the Duchess of Cambridge, both of whom channel more than a touch of Flotus in their wardrobes, wear purple – both, usually, as a crew-neck sweater with a white shirt or blouse collar showing over the top. The white collar is a cute everywoman touch, for aristocrats and royalty wearing purple, making the colour seem more down to earth.

The strongest purples are the bluish ones; the burgundy kind can be a bit school uniform. White always works with purple (popes and bishops know this); Michelle Obama wears it with black or navy, which is punchier. Purple with pink, however, or purple with blue, can look a bit Brash Wedding Outfit. For the same reason, I'd suggest we leave Jenny Jones's suggestion of a red hat that doesn't go and doesn't suit you as artistic licence. Also, the part about wearing it when you are an old woman. That's old-fashioned, that is.

• Jess wears dress, £699, by Stella McCartney, from harrods.com. Shoes, £235, stuartweitzman.com. Necklace, from a selection, jcrew.com.

Stylist: Melanie Wilkinson. Hair and makeup: Dani Richardson using Kiehl's Skin Rescuer.

There's so much more to this display of the late style muse's wardrobe than a bunch of crazy hats

It is a history lesson in hats

Did you know, for example, that in 18th-century France there was a fashion for elegant women to wear model ships in their hair, to celebrate French victories over the English at sea? I didn't, until I learned from the caption accompanying the "galleon" hat that it was this story, told by Isabella to Philip Treacy, that inspired it. Blow had a wealth of knowledge about history, and about the countryside and nature – she was a great lover of gardens, and roses – and a knack for plucking out colourful titbits with which to feed her proteges. Blow told her own story in hats: her fondest memory of her mother, who famously offered her 14-year-old daughter a formal handshake on the day she left the family home, was being allowed to try on her pink hat. The story she liked to tell about meeting her husband Detmar Blow began with him complimenting her hat.

It is a story about the power of fashion – and its limitations

The exhibition is a biography, in clothes, of a woman who once said that the mood-altering effect of hats was better than antidepressants, but who took her own life. Fashion was the great love of Blow's life, the focus of her passion and talent – but towards the end, she felt that the designers she had nurtured had left her behind. This is an exhibition with a very clear agenda: to give Blow the place in fashion history that she deserves. Driven in large part by her friends Daphne Guinness and Treacy, the show gives Blow a posthumous third act. In other words, this is not just hats, it is the backstory of modern British fashion being rewritten.

It is very funny

One of my favourite non-hat exhibits is a fax sent to Blow by an exasperated assistant during her time working at the Sunday Times, which conjures up a vivid picture of the thankless and impossible task of pinning the stylist down to budgets and RSVPs. Blow was very funny – she had a honking laugh, which Alexander McQueen said reminded him of a Billingsgate fishwife – and was uncowed by the worry that she might be thought mad. (Andy Warhol befriended her at a party, because she was wearing mismatched shoes.) At her funeral, her friend Rupert Everett described her as "a one-off ... your own creation in a world of copycats" and that bumptuous originality shines through here. The overall mood is bittersweet, but never maudlin.

This is an eyewitness account of the Cool Britannia era

Blow was instrumental in pushing into the limelight many of the key talents who defined Britain's renaissance as a creative powerhouse in the 1990s. Never a bandwagon-jumper, she was there right from the start. At Hussein Chalayan's graduate show, she sent him off to find a roll of bin bags, helped him pack the clothes in them, and marched him over to Browns boutique, where Joan Burstein put the collection in the window. At one point early in their careers, she had both Treacy and McQueen living and working in her Belgravia house. There was a kind of magic in the air: as Blow puts it, Treacy's incredible hats were appearing in his little basement studio "like muffins popping out of toasters". Blow "wasn't just providing money or opportunity, she was grabbing people by the collar and leading them into their future", says curator Alistair O'Neill. "I look at fashion now and I don't see who those people are."

Clothes that someone has worn are much more fun than an 'archive'

When O'Neill and the curators first examined the collection, they were hit by a wave of Fracas – the scent that Blow always wore, and with which McQueen perfumed the venue for his La Dame Bleue collection after her death, which was dedicated to Blow. "There is a very physical presence of Isabella in these clothes," says O'Neill. "We've got an exquisite McQueen hawthorn jacket which has a huge cigarette burn in it. Her hats were endlessly getting damaged where she would lean forward to light a cigarette off a candelabra at dinner." Sedately displayed on a pedestal are a pair of Givenchy haute couture mules, their silk-wrapped heels ripped to shreds at some party or another. There is a kind of innocence to this way of dressing, a storybook joie de vivre. Unfortunately, like all the best fairytales, it ends badly.

Isabella Blow: Fashion Galore! is at Somerset House, London WC2 from 20 November 2013 to 2 March 2014

From flamingo pink to classic cuts, Jess Cartner-Morley chooses a selection for your wardrobe

'Forget going to work on an egg: it's much smarter, now, to go to work shaped like an egg'

Just so you know, "That looks like a sack" is now a compliment. Power dressing has gone soft. Forget going to work on an egg: it's much smarter, now, to go to work shaped like an egg.

There are two reasons for this. The first is an inevitable backlash after the trenchcoat years. Such has been the dominance of belted gaberdine over the past decade that only waisted coats and jackets – trenches, but also military styles and Barbour jackets – have felt like status symbols. The second is that the arrival of groovy new young designers at the couture houses (Raf Simons at Dior, Alexander Wang at Balenciaga) has made the couture aesthetic feel relevant in fashion again, and the ovoid shapes, whether cocoon or sack-back, are a part of couture history.

Yeah, whatevs, right? What you want to know is: should you buy one? To which the answer is yes, and quickly. Nobody wants to buy a coat one autumn, only to have irritating people like me tell them a totally different style is necessary the next year. And the way to avoid that, my friends, is to buy into the new style as soon as it appears on the horizon, thereby securing maximum wear out of it. You need to get yourself a cocoon-shaped coat as a matter of urgency. (This is what passes for logic on planet fashion.)

When you've been used to fitted and tailored coats, there's something comforting about a cocoon shape. Belted coats are bracing, bossy; ovoid ones give you that fireside, wrapped-in-a-blanket feeling.

To ensure a softly curving coat looks smart, think about what you wear underneath. It is a silhouette that works particularly well if your general way of dressing is skinny-legged; that is, if you tend to dress in slim trousers or a short skirt. But if you wear knee-length skirts or wider-legged trousers, a long, lozenge shape on top will give you a weirdly droopy silhouette, so keep your cocoon short and sweet. An ovoid that curves out from the shoulder but neatly back in at the hip is an easy, goes-with-anything option. Buy one now. There's a good egg.

• Jess wears coat, £650, by Paul & Joe, from Harrods. Trousers, £288, by Vince, from Matches. Leopard sequin heels, £240, by Kurt Geiger London, from Kurt Geiger.

Stylist: Melanie Wilkinson. Hair and makeup: Dani Richardson using Kiehl's Skin Rescuer.

Lace dresses, thanks to their delicate transparency, are a winter classic for all occasions. Jess Cartner-Morley chooses a selection for your wardrobe

Suzy Menkes will receive special recognition at the British fashion awards. Too right – the bequiffed fashion editor is one of our industry idols

You may be surprised to hear that here on the fashion desk, our personal idols do not begin and end with Alexa Chung. On Monday, one of our all-time heroines will be honoured at the British fashion awards when Suzy Menkes, fashion editor of the International New York Times, is presented with the special recognition gong. Here's five reasons we love Suzy:

Her quiff

In the fickle and capricious world of fashion there is something marvellously comforting about the continuity of Suzy's Hair. That distinctive front-roll never changes from day to night, season to season. It is second only to Anna's Bob in front-row fame game. She invented it because she hated writing with hair in her face – and claims to be able to fix it "walking downstairs or along the street".

Her kick-ass reviews

She doesn't pick fights, but she doesn't pull punches. As Alber Elbaz of Lanvin puts it: "When we designers do a good collection, Suzy is so happy for us, and when we do a bad one she seems almost to get angry." Her ability to set fashion within a wider context gives her an agenda-setting edge: a piece that was politely critical of the legions of bloggers who, like selfie-obsessed, designer-clad cuckoos have hijacked fashion weeks and transformed them into a streetstyle circus practically sparked an industry civil war. Go Suzy!

Her passion

As a 19-year-old student at Cambridge in the 60s – where she was the first female editor of the Varsity student newspaper – Suzy fell in love with a pair of white Courrèges boots. "I wanted them so much, but we weren't allowed out of the college except in certain hours and we all had to wear black cloaks. I climbed out of college in the dead of night, over the high wall, using my cape, twisted, as a 'rope' to swing down the other side. I took the 4am milk train to London, bought the boots, got the train back, unrolled my crumpled cape and made it for the noon lecture." These days, Suzy will still be turning up to late, obscure shows, playing fast and furious with deadlines as she pounds out copy from her laptop, long after the twentysomethings have sloped off because their shoes hurt/Kanye West is rumoured to be showing up at a boutique opening.

Her niceness

Everyone is slightly scared of Suzy, but she's actually lovely. There is something of Mrs Tiggywinkle in her tinkling, old-fashioned accent and diction as well as the genuine, not-for-the-cameras girlishness of her smile.

Her chutzpah

Suzy crashed her first Chanel show by turning up at the venue at 5am with a broom and a mop and a handkerchief tied around her head, claiming to be a cleaner. She hid for four hours until show time, then ditched the hankie and crept out to watch the show. Awesome.

Anyone who is anyone is going to be at the BFAs. Kate Moss will also receive a special recognition award, and Marc Jacobs and Miuccia Prada are rumoured to be attending. And you can be there too – tickets cost from £45, and are available from britishfashionawards.com/tickets. Get yours now – and then can we PLEASE discuss what on earth to wear?

'There's something in the ritual of lace that draws us to it at the time of year when tradition matters most'

Around this time of year, each year, I start to crave lace. Mulled wine, mince pies, insanely expensive, small, decorative woodland animals, and lace. Every festive season, regular as clockwork, nothing whatsoever to do with fashion. Luckily, I'm not alone: also around this time, every season, with cheerful disregard of what was or was not on the catwalk, every store you walk into is selling lace dresses.

It's a skin substitute, you see; that's my theory. In summer, when the spaghetti-strap vests come out as soon as the mercury hits 24 degrees and shorts are the default bottom-half uniform of the entire population under 35, you can get up close and personal with as much bare flesh in the average lift as you would in a hot tub in the Playboy mansion. But come October, our skin disappears under a tortoiseshell of 60 denier opaques. And by now we're missing skin, and lace is the next best thing, so out come the lace party dresses.

It's not just perviness, to be fair. There's something in the ritual of lace that draws us to it at the time of year when tradition matters most. Miuccia Prada once said lace tracks women through their lives, from christening gowns to wedding dresses, lingerie to mourning garb. She missed out Christmas parties – perhaps they're too chic, at Prada, for Wham! and Secret Santa – but she's on to something. Lace is a touchstone for special-occasion dress, a lucky charm for nights that feel important.

The meaning of lace changes with the colour. White is holy and snowy and untouchable. Red is raucous and festive, a here-come-the-girls clap-and-shriek of a fabric. Black means sex or death – sex, generally, unless you drape it over your head and sob, which is a bit un-Christmassy. Navy, dark green and burgundy are the hardest to pin down – and, therefore, perhaps the easiest to wear.

But in any colour, lace is a promise of, and so a substitute for, bare skin. In other words, you don't need lots of both. A long lace dress with slim lace sleeves looks very grand, and instantly rebuffs any suggestion of sleaze; on the other hand, a slip-of-a-thing nightie dress looks more chic with a lace trim than in all-over lace. No need to overegg the pudding. It's not quite December yet, after all.

• Jess wears dress, £790, by Carven, from harrods.com. Shoes, £235, stuartweitzman.com.

Styling: Melanie Wilkinson. Hair and makeup: Dani Richardson using Kiehl's Skin Rescuer.

The leather skirt has been considered risqué – but now it has gone mainstream. Jess Cartner-Morley chooses a selection for your wardrobe

'Leather has been mainstreamed. It isn't foxy or rude or stick-your-neck-out, any more. Let's celebrate'

It is not often fashion welcomes a genuinely new species but today I stand before you in a genuinely freshly minted fashion garment. Not a revival or a rehash, but a crossbreed made possible by advances in scientific thinking. Yes, sort of like the cockapoo, but less fluffy. Ladies and gentlemen, I give you: the Respectable Leather Skirt.

Leather has been mainstreamed. It isn't foxy or rude or stick-your-neck-out, any more. Like leopardprint, it used to be decidedly risky, but is no longer even risqué.

There are two forces at work here. The first is that the mass fashion industry has figured out how to produce leather economically, so a once-exclusive fabric is now on every high street, making it, inevitably, a little less remarkable.

The second factor is that the sexiness of leather feels ever more tame, as the pop cultural fashion lexicon out-raunches itself. Curious to recall, now, that a tight leather skirt to, ooh, the mid-to-upper-thigh, used to be what particularly saucy pop stars wore in videos. In the age of Blurred Lines and Wrecking Ball, wearing any sort of a skirt in your video basically marks you out as an old square. Miley would surely laugh in the face of a stylist who dared suggest anything as old-ladyish as a leather skirt.

Which is fine by us old ladies. Because we are now free to celebrate leather's unfeted practical side. For anyone who eats lunch at their desk – especially those Pret salads with the springy bits of frisée that bolt Houdini-like from even the most careful of fork work and find their way into your lap – a leather skirt is, frankly, genius, because it is wipe-clean. Dab of Kleenex and you're right as rain.

And, once you liberate leather from the requirement to be sexy all the time, it has unlimited possibilities: this season, primarily, as a longer-length skirt, one that works perfectly with a blouse or a posh sweatshirt, and that has the demure swish of a lady's petticoat combined with the toughness of a blacksmith's apron. Leather, like a once-rough neighbourhood, has been gentrified. Celebrate with an overpriced coffee (and no need to panic if you spill it.)

• Jess wears shirt, £100, by J Crew, from netaporter.com. Skirt, £95, whistles.co.uk. Shoes, from a selection, dunelondon.com.

Hair and makeup: Sharon Ive at Carol Hayes Management using Lancôme.

She won't do eveningwear or work for anyone else. But after 20 years in the fashion industry, with vast queues for her new range at H&M, French designer Isabel Marant has burst her niche

Fresh off the Eurostar from her home in Paris, the fashion designer, wrapped in fur, takes a seat in her Mayfair boutique and sips her coffee. But no, erase that mental image: Isabel Marant may be the buzziest fashion designer of 2013, but she is nothing like that sounds. In flat black suede boots, skinny leather trousers and a grey cashmere crew neck layered over a white T-shirt, she looks less like a Paris fashion week diva than a chic yoga teacher. The fur jacket she is wearing sells for several thousand pounds, but she tugs it around her shoulders as if it were an old blanket; she likes the salt-and-pepper colour, she says, because it matches her silvering hair, which, at 46, she does not dye. On the shopfloor, designer armchairs have been regally placed at either end of the immaculate cream rug, punctuation points intended to emphasise this grand expanse of top-dollar real estate. Marant picks one up, drags it towards the other and sits down, hands around a mug of coffee, leaning towards me between her knees as if we were beside a campfire.

Isabel Marant's clothes have been a fashion insider's obsession for a decade, but this year the brand went global. Since the label's inception in 1994, fashion has been increasingly dominated by multibrand, global powerhouses such as LVMH, but Isabel Marant has bucked that trend, growing steadily while remaining independent. The clothes are now sold in over 800 boutiques and department stores worldwide. With her recent H&M collaboration, Marant joined a rollcall that includes Versace, Lanvin, Martin Margiela, Stella McCartney and Karl Lagerfeld, and the publicity around the range has strengthened her place in the fashion constellation, shaking off any vestiges of a too-cool-for-school image. The newly opened London boutique is just a few hundred yards from the H&M stores where, three weeks ago, crowds queued overnight for the chance to buy the fringed ankle boots, studded rock-chick jeans, washed-out sweatshirts and slouchy cardigans that are staples of Marant's brand. (Many items from the sold-out H&M range are now available on eBay at a 1,000% mark-up; this is no less expensive than shopping in the Mayfair boutique.) Marant is cheerfully unsnobbish about embracing the high street. "I was flattered that they asked me, actually. Very proud, because H&M had worked with so many of the best designers that to me this meant I was a real established designer."

Marant defines her brand as "a silhouette and an attitude". I ask about her clothes, fabrics, inspirations; she answers me with a gesture or a pose, rather than a description of colour or style. "A jacket should be a bit … you know", she says, filling the gap with a loose-limbed wriggle of her shoulders; or "when you wear jeans you feel … cool, you know" with a crossing-and recrossing of her slender legs. "I want my clothes to be perfect – but easy-perfect, you know?", she adds, plucking briefly at the cuffs of her sweater, to show how they finish at exactly the right point, just beyond the wrist bones. French women are different from English women, she says, in that they will "pretend they are not paying attention to how they look, but really they are. I dress the same every day, but I love everything that I wear. A nice, leather trouser, a nice flat shoe, a nice linen T-shirt, cashmere, fur." How long does it take you to get ready, in the morning, I ask her. "One minute," she fires back, huge grey eyes unblinking.

There are two traditions of French chic, of course: the lap-dogged and coiffed, coutured and gold-buttoned Avenue Montaigne type, and the bohemian, Rive Gauche strand. Marant is the latter; her smile makes her look a little like Jane Birkin. She has a marvellously Hercule Poirot diction ("my eye, it is trained, of this I am certain") enhanced by her low, raspy voice. (She smokes roll-ups.) Her hair is in a messy bun fixed with a black elastic tie – but she is careful to restyle it before she has her photo taken. She has a marvellously mobile, expressive face which is ageing enviably into a burnished olive patina, like a mirror foxed with age. She wears almost no makeup, perhaps a smudge of eyeliner, but her thick eyebrows are perfectly shaped and the scrubbed glow of her face suggests expensive moisturiser. Her nails are unvarnished, but gleamingly neat.

Marant designed the prototype for the concealed-wedge high-top trainers that became her best-selling, most-copied product when she was just 11 years old. "I was a tomboy, so I would never wear heels. I wanted to look taller, but I wanted to look cool, so I put pieces of cork inside the sneakers. I just think it's the coolest thing, to be in sneakers, but to be taller." The wedge trainer – copied so widely, Marant says, it is "disgusting!" – captures the DNA of her brand: androgyny with feminine wiles. "It was only a few years ago that I thought of going back to that idea I had had when I was 11. But I knew it would work. Because a high heel in your shoe positions your body in a certain way, it gives you confidence. And you are comfortable. You feel good, basically."

Marant's German mother was a model, "beautifully dressed, a lot of Kenzo". Her parents divorced when she was little; later her father remarried "a very chic black woman, always in Yves Saint Laurent. So, I grew up surrounded by beautiful clothes. Of course, at the time I didn't like it – it turned me into a tomboy, but I learnt a lot. I grew up wearing my father's old cashmere, making something out of his best Harvey Nichols robe with the silk lining." At 16, she was selling the clothes she made: skirts made out of the coarse, red-and-white striped cotton of traditional French kitchen linen. "I was obsessed with Vivienne Westwood. A bit crazy. Supergrungey!"

She studied at the prestigious Studio Berçot in Paris, and later worked as a fitting model for Michel Klein, wearing early versions of the clothes in the studio, so the design team could see how they worked on the body. "I learned a lot from that, because as the fitting model you see the clothes from the woman's point of view, and from the designer's point of view. That's still how I think when I work." Before long, Marant had launched her own label, with her first catwalk show held in a squat, with friends as models. "No one else was designing the clothes I wanted to wear, so I made those clothes, and I found other women who wanted them, too." It wasn't long before a word-of-mouth cult label was born.

The nicest thing any journalist has written about her clothes, she says, is "that they look like clothes you already have, that belong in your wardrobe". She looks thrilled, which is striking, as she is hardly starved of praise: every stylist in Paris seems to see Marant as the cool older sister they never had. But Marant loves the idea that her new clothes look like old favourites. "I love old clothes, the way they fall. A leather jacket that has softened into your shape – there is nothing prettier."

Where other designers charge endlessly through new territory to ring the changes Marant's aesthetic is more zen. The metaphor she uses is cooking. "I am stirring, and tasting, and adding seasoning, always thinking, is this right? Is it perfect? And everytime I cook the same dish, it tastes a bit different." She makes tiny seasonal adjustments – "it could be a gesture of a woman in the street that makes me notice how her jacket falls, it could be a fabric, a length, a feeling" – to update a look, though its essence never really changes. "People come here to buy the essence of Isabel Marant. I start with myself but I also think about all the women who work with me, and how women want to show different parts of themselves, hide different parts. Sometimes it's about how a garment falls that makes it feel special, that makes a woman feel good. And you always have to have the pocket in the right place, to flatter the hips. Mostly I just do what I like, but when I am really in love with something that I design, usually that piece will be the bestseller. It's funny seeing this autumn collection on the rails now, because when it was finished I thought to myself that it wasn't my strongest. But now it comes to this time of year and this is exactly what I want to wear this winter. And all those leggings, those long sweaters – they are sold out."

One of her motives for agreeing to the H&M range, she says, was the chance to recreate personal favourites from past collections. "I have some things I made ages ago that are the first things I put in any suitcase, and one day I thought: what happens if this suitcase gets lost? These are my treasures. At the end I was so surprised, because I am not usually a crazy person for new clothes, but I ended up buying some of the pieces. Of course I could order what I wanted but some of the things I didn't think I would want, and then I saw them on the shopfloor and I bought them." The oversized knits – "my Big Lebowski cardigans"– are her favourites.

Marant does not design eveningwear. Her nose wrinkles at the word. "I hate it. I don't think it's modern. It's as if you are disguising yourself."

For a designer, this is a significant decision. Red-carpet dressing takes up a growing proportion of fashion coverage. But she is adamant.

"That's just not how I want to look. I love to do something feminine, but I put it with something masculine, because for me that is harmony. If I do white, I will do black."

Marant is married to Jérôme Dreyfuss, an accessory designer, and they have a 10-year-old son. They live and work in Paris, but their "salvation" is a cabin with no electricity 50km away. "It is tiny, just a small, wooden house by a river. It's more like a boat, in a way – we have a gas stove, we have candles, and when night falls, we go to bed." On Saturdays they work in the garden.

"We don't even have a letterbox. It is very reassuring to know you can live with almost nothing."

Her one regret is that she launched her own label before working for anyone else, but at this point she rules out taking a job at a major house. The brand will continue growing, she says, "for as long as it can grow and stay the same. I won't let it change, or it won't have a soul. I am proud I have many of the same employees working with me since the beginning. I want to expand, but it's more important to keep my roots. I'm good at doing Isabel Marant, and that's it. Why do anything else?"

Jess Cartner-Morley chooses a selection of new-generation status jackets that are a lot cheaper than the classic Chanel version

Jess Cartner-Morley: When you think of Chanel, you think of … Texas, right? Maybe not. But Karl Lagerfeld likes a challenge, so Chanel staged the latest Metiers d'Arts catwalk show in Dallas

'There will always be a need for a status jacket'

There is power dressing, and there is status dressing. Power dressing is about work; status dressing is about a more subtle wielding of position, wealth and influence. Society women had status dressing, even back when only actual queens had power. These days, women have both kinds.

The jacket I am wearing here – the soft, shruggy, look-at-me, non-blazer jacket – is most definitely not a power jacket, but a new type of status jacket. I would call it the Post-Blue Jasmine Jacket, if that wasn't just too esoteric even for moi. If you saw the Woody Allen film Blue Jasmine, or even if you only saw the posters, you may remember the cream Chanel jacket that Cate Blanchett's character wears. The way she clung to that jacket, like a soldier stumbling home from war in bedraggled uniform, seemed so desperately sad that it made me realise how the Chanel boucle jacket – which has reigned unrivalled as the blue-chip status jacket for ladies who lunch, as well as for ladies whose power is so unassailable that they are free to flirt with feminine whimsy in the boardroom – is beginning to fade in lustre, as even the most timeless classics will. The Chanel jacket will no doubt be back – this was its second or third coming, after all – but for now its tweed and pearls have a wilting kind of grandeur, like the insignia of a mighty army in dignified retreat.

This leaves a potential wardrobe vacancy, because there will always be a need for a status jacket, not only for trophy wives, but also for those in possession of position, wealth and influence in the sense of it being payday and them having bagged the best table in the bar. The Post-Blue Jasmine Jacket is deliberately, defiantly informal. It might channel the quilted, Saturday-morning-yoga jackets of Isabel Marant, or Jonathan Saunders' bumptious hipster bombers. The colours are brighter and sharper than the blended tones of Chanel boucle; the silhouette sporty and round-shouldered, rather than feminine and feline. It's a completely different jacket, but it means exactly the same thing. Update your lexicon accordingly. And if you don't believe me, watch the film.

• Jess wears jacket, £39.99, mango.com. Jersey, £18, topshop.com. Jeans, £165, by Paige, from paigeusa.com.Shoes, £240, kurtgeiger.com.

Hair and makeup: Sharon Ive at Carol Hayes Management using Lancôme.

Don't panic. The high street is full of stylish, glamorous and affordable solutions to 11th-hour present dilemmas

Forget mulled wine, Bing Crosby or queueing in the post office: there's one thing that really captures the spirit of this time of year, and it's quite possibly in your coat pocket right now. Yes, it's that scribbled list of names on the back of an envelope that represents all the people you still have to buy presents for. In the festive marathon, this last week before the Big Lunch is the lap where the scent of cinnamon is tinged with a sniff of panic. You have some shopping to do, sharpish.

Fashion is the answer to your prayers. Don't snort in that cynical way, it's not Christmassy, and anyway, I'm serious. Fashionable presents are often overlooked, either because we think they will be too expensive, or because the sizing issue seems fraught with danger, or because the concept of other people's taste seems too opaque. This is all nonsense. The high street is full of mood-boosting fashion quick hits that avoid making comment on the perceived size of the recipient's thighs. And as for their taste: no one is going to be insulted that you chose them a gift because it was chic and glamorous. Believe me, buying her a new Dustbuster instead is not a safe option here, however useful it might be.

The simplest formula for fashionable Christmas shopping is to find NICE VERSIONS OF USEFUL STUFF. This way, it doesn't matter if they already have it. The key is to make it nicer than what they would buy themselves. This is why lovely socks are genuinely a nice present (although lost on the under-30s, who will look nonplussed and wish you'd given them the cash to spend on drugs). This year's buzz haute-high-street label J Crew has great classic cotton pyjamas, white or pale blue, for £95. A posh tote bag, for carrying shopping/gym kit, is an essential for most women: Gap has a beautiful leather version for £79.95 (pictured above).

Next, KNICKERS. The rule here is to give underwear only to people with whom there is absolutely no ambiguity as to whether or not you wish to shag them. In other words, if you're a woman, you can give boxer shorts to your husband and knickers to your best girlfriend but this genre is best avoided in any relationship where misinterpretation is a possibility. Also, in the spirit of Christmas togetherness it is worth remembering that many people find watching someone unwrap a box of frothy Agent Provocateur lace a discomfiting Public Display of Affection. If you are going to be unwrapping gifts in front of a teenage nephew who will be mortified, please keep it clean. The best option for special but non-pervy undies is Stella McCartney, which has these tiger-stripe knickers for £21(above).

A fashionable take on PRACTICAL CLOTHING is a good way to add a bit of fun into gifting the pragmatically minded – men, as well as women. Very light down jackets and gilets, perfect for layering under a coat for a Boxing Day walk or a New Year's Day trip to the football, are a smart option here. The Uniqlo range is particularly good, and great value at around £60. Try to get one in black, obviously. If they do any kind of sport or exercise, buy them something for that. Good sports gear is surprisingly expensive, and the sort of thing one scrimps on for oneself. Nike's website is easy to navigate and can be searched by sport or genre; for women, Sweaty Betty has lovely stuff for running and yoga. Stella McCartney for Adidas is great value for a Stella aesthetic, and very functional. We love these shorts and matching jacket, £50 and £140 (pictured above).

At the opposite end of the spectrum, don't underestimate the power of buying SOMETHING TINY FROM AN AMAZING LABEL. The Outnet – which is sort of like a permanent, enormous sale rack for Net-a-Porter - has this leopard-print top by Michael Michael Kors for £42. This skull-print scarf (above) by Alexander McQueen is £165, but a stone-cold classic; anything by Saint Laurent – Matches has a leather bracelet for £215– is a blue-chip present.

If that sounds like a total waste of money, take the opposite approach with a beautiful piece of HIGH STREET CASHMERE. Two pieces that I can vouch for as fabulous in the flesh are a cashmere hoody by M&S, now reduced to £83.30 in the sale; beautifully indulgent whether she wears it on the sofa or out to lunch. If a hoody seems a bit teenage – although they are still a wardrobe staple up to the early-40s, I find – this Off Duty Jumper by Boden above, is £160.65 (in the sale), gorgeously thick, sumptuous and flattering. Frankly, anyone who sniffs at the label after copping a feel of this cashmere is an ignorant snob.

If you are department-store shopping, head for small leather goods. WALLETS, MAKEUP BAGS AND iPAD COVERS make great presents. Look for something from a label that will feel relevant to the person you are buying for. Youngsters will love Marc by Marc Jacobs. This makeup bag, £35 from Harrods (shown above), for instance; quarter- to mid-lifers will go for a bit of Diane Von Furstenberg; Tory Burch is a good choice for more traditional tastes. And everyone loves Mulberry. This Mulberry leather makeup bag is £195, which sounds a ridiculous amount to spend on a makeup bag, but she'll use it every day and it will last for years.

If you have the budget for a whopping pair of emerald earrings from Cartier then she'll love you for ever. Well, almost certainly. But don't disregard jewellery just because you don't – FUN JEWELLERY is a lovely gift. Grownup friendship bracelets such as this moonstone Astley Clarke one, £85 (above) are a wear-now present that don't have to be for ever. If she likes pretty earrings, Lulu Frost is a hot label right now, and not super-expensive. Wolf and Badger is a good website on which to find inexpensive jewellery, including a Glenda Lopez ring with a tiny gold hot-dog, £41.

A FRIEND WHO LOVES FASHION but doesn't have loads of free time to shop will be really touched if you do the high-street trawl for treasures for her. Price tag and the name on the label don't matter here. Zara, H&M and Topshop should be top of your hitlist. Avoid things you need to try on, for obvious reasons. Clutch bags are a particularly good option right now, as few of us have nice, modern-looking ones. This Zara minaudière box clutch, (above), £29.99, is a brilliant fast fashion find. (The label also has a clutch with a glass clasp, also £29.99) If you brave clothing, an embellished sweatshirt is a good choice, as fit isn't super-important and the comfy-but-jazzy combination makes it perfect for Christmas. Topshop has a grey sweatshirt with beading for £40 that is worth a look.

One annoying thing about MEN is their tendency to remain unmoved and unsquealing at the silly, sparkly presents that get women all excited. Our gift-buying culture overcompensates for this by producing "gifts for dads" which are jokey in a boom-boom way that makes Bruce Forsyth look like Woody Allen. See: mugs and T-shirts with self-deprecating slogans about dad's uselessness/shed obsession. It is important to rise above this, because the Jokey Dad presents are the ones that sit awkwardly on a shelf for a year and then get binned. They want dull? Don't fight it – give them dull. For instance, these cashmere and silk socks, £15, from Marks & Spencer (above).

You can buy expensive French gear for newborns, because they've got no idea what's going on and Mum will love it, but most small CHILDREN don't see clothes as proper presents. After about age seven, it becomes a good option again. For younger kids, go for something fun. This girl's handbag from Monsoon, above, £10, is great because kids love stuff with animals on. H&M is an inexpensive source of sweaters and leggings with puppies on for younger children, and teen-styled hoodies and sweatshirts that will appeal to tweens who wanna be teens. An element of fancy-dress makes clothes seem fun to kids: H&M has a tutu-ish tulle skirt, which is a steal at £2.99.

Jess Cartner-Morley makes a prediction for a new trend for jeans - the party jean. She selects a few pairs that would look good on anyone