It’s the million-dollar question for power dressers everywhere: have tights come in from the cold?

There are three fundamental questions that must be addressed at this point in every year. Question one: is it time to switch the heating on? Question two: whose family are we having for Christmas? And, drumroll, question three: can we wear black tights?

The first two are mere detail; the third is everything. The opaque tights issue is a thorny one in fashion. It divides women along class and generational lines. Class lines, first, because going bare-legged in winter is a high-maintenance choice. To put it bluntly, having your legs bare in winter is no hardship if you have a driver waiting; it is perfectly doable if you must wait four minutes for an Uber; it is a battle if your bus isn’t coming for 20.

The royal baby news has put the Duchess of Sussex’s maternity style in the spotlight. How will she navigate ‘bump watch’?

Being modern is Meghan’s USP. She is the modern duchess, hauling the royal family into the 21st century with her artisan elderflower cakes and feminism and cross-body bags. And now, with The Happy News, Meghan is navigating a very 21st-century challenge: how a thirtysomething first-time mother incorporates a baby bump into the sleek, streamlined identity of the independent-minded modern woman.

Meghan’s maternity wardrobe will be scrutinised and debated almost as much as her wedding dress. Getting pregnant while newly minted into the royal family, when the spotlight on her is at full beam, will make the focus on Meghan’s maternity look even more intense than it would have been in a year or two. There has been no shortage of royal babies this decade, but poor Kate was so wretchedly sick that she had to be excused from smile-and-wave duties for much of her pregnancies, so the public appetite for princesses-with-bumps is far from sated. And anyway, it was all very different with the Duchess of Cambridge. Kate’s USP was simply that she was Not Posh. She didn’t have a triple-barrelled name that sounded like an Austrian ski resort and people in her family had actual jobs, and that was enough to blow our tiny minds back in the innocent days at the beginning of this decade. We didn’t expect her to be modern as well. That’s where Meghan comes in.

It sounds vaguely rude but just means wearing a long knit, jacket or light coat over trousers or a long skirt

The top I’m wearing here isn’t in the shops – it’s from my own wardrobe and about five years old, so you can’t buy it. So it goes against the No 1 rule of fashion journalism: in order to be useful, I wear and write about stuff that you can go out and buy. Well, if it’s all right with you, I’m going to do things a bit differently from now on.

We’re all trying to shop more ethically, to not mindlessly buy clothes that will end up in landfill, right? I thought a good place to start would be by mixing up this column so that I’m still wearing a new look every week without being head to toe in new clothes. I’m hoping that since this is how we all actually dress anyway– wearing old favourites with new pieces – it will be more useful, rather than less.

Related: The skirt suit – but not as we know it | Jess Cartner-Morley

If you love clothes, it makes no sense to treat them as disposable. Do we need to buy a new coat every year?

It is late October, which means there are precious few days left when you will see daylight on both sides of the office, that Strictly is starting to get interesting, it is 10-to-Christmas already – and in fashion terms, it is time to buy a new coat. Some things never change.

Except, maybe they do. Or rather, maybe they should. If you love clothes, it makes no sense to treat them as disposable. Does anyone need to buy a new coat every year? Possibly, if you buy just one coat and wear it day in, day out in all elements. But if you spend the winter flitting between your work coat and your going-out coat and your super-practical, really-hope-no-one-sees-me coat, then you’re not wearing any of those coats thin. Also, don’t know about you, but I’m getting older, and I swear that a year goes by now in about 10 minutes, so doing anything once a year feels like a more hectic schedule than is absolutely necessary.

Related: How to wear downstairs layering | Jess Cartner-Morley

This is a shop-your-wardrobe opportunity, because you can wear the same sequins you used to wear after dark

Sequins used to have a 9pm watershed, like sex and swearing on telly. You wore them to parties, for nights when you were not just out but out-out, but they were decidedly NSFW. Now that you can wear jeans to parties and trainers to fancy restaurants, those kind of rules don’t really apply. I’m not suggesting a sequined skirt is a 16-hour desk-to-dinner look, but it could definitely do a Saturday lunch – possibly even brunch, although be prepared to drink mimosas. (That is totally going to happen in this skirt, so you may as well face facts.)

This is a shop-your-wardrobe opportunity, because you can wear the same sequins for the daylight hours as you used to wear for after dark – you just wear them in a different way. The skirt I am wearing here is one of mine that used to be a dress, a long time ago. It was a simple, stretchy, short-ish dress with spaghetti straps that I used to wear out-out with ankle-strap sandals and a denim jacket. I stopped wearing it like that a while ago. I’ve little truck with rigid rules about what’s age appropriate, but I don’t think clinging determinedly to a look that represents who you were a decade ago is all that healthy. You and your wardrobe can evolve and mature without going full pelt into elasticated-waistband loungewear.

Related: How to wear: your old coat | Jess Cartner-Morley

A year after buying mine, I’m starting to get the hang of it

Checks are very much in this season. This dress, for instance, is by Ganni, which all the cool girls are wearing, and it’s in the shops now. The jacket I’m wearing isn’t in the shops because I bought it from Topshop in August last year, when check blazers were just becoming a thing. So it’s technically three seasons old, although Topshop has several similar styles this season, including a navy windowpane number for £65, which I would be tempted by if I didn’t already have this one.

Although it’s well over a year old, I still think of this as my New Check Blazer. Partly because I swear a year zooms by in about five seconds – dry cleaning the curtains is only one of many jobs that have been on my to-do list for much longer than this blazer has been in my wardrobe – and partly because I am only now getting into the swing of wearing it.

Related: How to wear: your old coat | Jess Cartner-Morley

Profits are plunging at Victoria’s Secret as a proudly bra-less look takes hold. The most fashionable boobs are now no longer in your face

Victoria’s Secret has a whole bunch of problems right now. Last week’s New York fashion show has been overshadowed by comments made by its boss, Ed Razek (for which he has since apologised), about how it would be inappropriate to cast “transsexuals” in a show “about fantasy”. Profits, sales and market share have all fallen over the past year; most alarmingly, month-by-month breakdown shows the decline growing steeper still. But neither of these are the brand’s biggest problem. The real trouble for Victoria’s Secret is that it is selling the wrong kind of cleavage.

All breasts are beautiful, but some are more fashionable than others. The scaffolded cleavage – hoiked and cantilevered by a push-up bra, twin globes held rigid – is still the style at Victoria’s Secret. On the New York catwalk, Gigi Hadid wore a shiny blue check bra with matching knickers, a billowing tartan cape and a bumbag in the style of a sporran. Kendall Jenner was dressed in a black and silver glitter push-up bra with a multistrap knicker-harness hybrid and frilly wings. There was the odd legging-and-sports-bra concession to athleisure, but the hoisted boob reigned supreme. And, in 2018, this is the wrong kind.

Related: Is it legal for your boss to make you wear a bra to work?

This festive season is all about optimism. Cross your fingers for Santa to bring you a tuxedo dress

‘Tis the season to be jolly. This is literally the whole point of Christmas. OK, not literally – but pretty much, since in this chapter of late capitalism the tale of Bethlehem effectively functions as the backstory to Elf and outdoor skating rinks. The point of Christmas is merriment, togetherness, gratitude and hope. And the point of party season is to get the festivities started as soon as possible, via the squad’s Secret Santa and annual drinks tradition.

It’s the perfect foil for a huge pair of earrings – reason enough to endear the look to me

This isn’t why I did it, honest, but an unexpected benefit of this column becoming more sustainable through wearing and talking about the clothes we already have, as well as pieces you can buy, is that I get to make out like I was on to all the new “lewks” before anyone else was.

For example: the boat neck. You probably think it was Meghan Markle’s Givenchy wedding dress with its wide-slashed, high-rise neckline that rebooted this style, don’t you? Well, sorry, Meg, but I bought this navy velvet top two years ago, from Finery. (It was £45. Finery is such a bargain.) True, I may not have worn it in front of a television audience of 18 million but I did wear it to see Rogue One: A Star Wars Story at the Vue at the Angel Islington, and to Byron afterwards. (Hey, it was 2016.)

Related: How to wear downstairs layering | Jess Cartner-Morley

Designer aiming to make business case for why brands should tackle climate change

Stella McCartney is to announce a United Nations fashion industry charter for climate action, which will be launched at next month’s climate talks in Poland.

The designer hopes the charter will “ring some alarm bells” while making a business case for sustainable fashion, setting out a path for collective action to enable low-carbon production methods to be scaled up, improving economic viability. Other signatories to the charter, which will be launched in Katowice on 10 December, have yet to be announced but are known to include several major fast fashion brands.

The charter has been initiated by the UN climate change secretariat. Waste, pollution, deforestation, toxicity in manufacture and carbon-fuelled supply chains combine to make fashion one of the most environmentally damaging industries, and reform is essential if the goals agreed in the Paris climate agreement are to be met.

There are signs consumers are driving a move towards responsible consumption. A report by the fashion search website Lyst, which tracked more than 100m searches over the past year, shows a 47% rise in searches that combine style and ethics, such as “vegan leather” and “organic cotton”.

“We really don’t have long now, to change things. But I honestly believe it’s doable – I couldn’t do what I do if I didn’t believe that,” said McCartney. “There is so much guilt and fear attached to talking about sustainability and that’s not helpful. What is essential is for the big players in the industry to come along with me, because that changes the price point.”

Related: Cheap fashion sales threaten the planet. Could online influencers be our saviours?

If you wear colour, wear all colour; if you wear black, wear all monochrome. It’s that simple

Is it more modern to wear head-to-toe colour than all black these days? Ha! Trick question. Either is fine. Sometimes I see a woman in an unusual colour combination and think to myself, she’s clearly a genius – from now on, I’m only ever wearing lavender with navy, or lime with aubergine, or whatever. But then, the next day, someone in a black trouser suit over an inky rollneck slinks past and I take it all back.

It has to be one or the other, though. It’s not about giving up black; it’s about giving up filling in the gaps with black. Filling in the gaps with black is a thing we all do, without even thinking about it. Wake up in the mood to wear a bright pink sweater, automatically reach for black jeans to wear with it. Or, having been seduced into buying a new winter midi skirt in emerald green or peacock blue and figuring out how to wear it, try it on with every black top in sight, without considering any other colour option.

Related: How to wear: the boat neckline | Jess Cartner-Morley

Everybody loves Michelle Obama. That’s not my opinion, it is a fact. I know this because I have been reading her memoir, Becoming, and every time I take it out of my bag, someone tells me how much they love her – my hairdresser, who put his scissors down to stroke the glossy cover reverently, a lady next to me on the tube, almost everyone on Instagram. Two teenage girls in Starbucks, who were waiting for their toffee nut latte frappuccinos, waved at me, pointed to the book and made love-heart shapes with their hands.

As a result, you would have a better chance of catching a glimpse of Father Christmas when he comes to town this December than Michelle Obama. Tickets to her talk at the Royal Festival Hall in London sold out in moments, and she has cosy couples’ dinners with friends including the Clooneys and the Duke and Duchess of Sussex to squeeze in while she’s in the UK. And yet, you can’t miss her. Her image is everywhere. It has been two years since the end of Barack Obama’s presidency, and this is the second coming of Michelle. She is no longer a plus one. This time around, the first lady comes first.

Metropolitan Museum of Art’s Temple of Dendur becomes catwalk for Metiers d’Art show

When Coco Chanel visited New York in 1931, the Chicago Daily Tribune noted that she arrived with two assistants, three maids, 15 trunks and 35 additional pieces of luggage. Eighty-seven years later, the house she founded still travels in style.

On Tuesday the Metropolitan Museum of Art rolled out the red carpet for Chanel and hosted its first fashion show in three decades, turning the Temple of Dendur in the Sackler Wing into a catwalk for Karl Lagerfeld’s Metiers d’Art collection.

Related: Versace harks back to greatest hits with savvy New York show

Tess Daly and Claudia Winkleman wear grownup party clothes: block colour jumpsuits or little black dresses, long dresses with splits or boxy minis

I don’t really see the point in going out on a Saturday night between October and Christmas. What could you possibly do, where could you possibly go – crucially, what could you possibly wear – that would be more glamorous than Strictly? Camaraderie, dancefloor elation, gossip, the full Saturday night package, is delivered to you at home so you don’t have to move. Bliss.

In the unlikely event that I do leave the house on a Strictly Saturday, I take the dress code with me. Not the maribou-edged nudity of the dancefloor, obviously. Instead, the dress code that applies to presenters Tess and Claudia. Every week, those two wear the grownup party clothes: block colour jumpsuits or little black dresses, long dresses with splits or boxy minis. In the Strictly narrative, the dancing couples are all hormones and tears, babbling a mile a minute about how tonight is the most amazing thing that has happened to them like alcopop-fuelled teenagers. Tess and Claudia bring a little grownup perspective, with (respectively) a steadying arm around the shoulder and a dose of wry humour. While everyone around them couples up in Strictly’s weekly parade of state-licensed infidelity, Tess and Claudia are each other’s constant wingmen.

Related: How to wear: sequins in the daytime | Jess Cartner-Morley

Snowman earrings and big-name trinkets are a good bet. But watch out for misleading rings and chunky strong-and-stable necklaces

Look, I’m not pretending diamond earrings wouldn’t be nice. But the days when jewellery was just hard currency in sparkly form are over. Costume jewellery isn’t about fake jewels any more, it is desirable in its own right. Most women who wear jewellery buy it for themselves, change it frequently and love getting it for gifts. You can get fun jewellery on the high street for a tenner and longer-term jewellery-box treasures for well under £100. So a pair of earrings or a necklace isn’t just a landmark birthday present any more – it might be the answer for your aunt or your office secret Santa or your kid’s year-three teacher. Try Zara: I love these black velvet teardrops dangling from beaten-gold domes studded with black rhinestones, for £12.99.

Related: Glitter bug: 12 of the best sparkle accessories - in pictures

From a fashion point of view, 2018 peaked – or rather, troughed – one Thursday in June, when the US first lady wore a green army jacket emblazoned with the slogan “I really don’t care. Do U?” to visit a shelter for unaccompanied children. Many of the children were in the Texas facility after being separated from their parents, an immigration policy for which President Trump was being denounced as heartless.

The jacket was 2018 in a nutshell. A story almost laugh-out-loud in its absurdity, and yet deadly serious. (The strapline for this year could surely be: “Yes, that really happened.”) An outrageous White House play that became a lightning rod for the spotlight. A Trump move that does not even pretend to appeal to voters’ highest instincts, but instead encourages their darkest, meanest side with an enabling wink.

The challenge is how to dress up without grandstanding. A nice blouse is just the thing

This is not a white shirt. It is a cream blouse. Big difference. A crisp white shirt is no good to anyone – not for the next week, anyway. Your white shirt can stay in the ironing pile until 2019, when it will be just the thing to get you in the back-to-work zone. Until then, you don’t need a shirt. What you need, instead, is a blouse.

A blouse is the feminine version of a shirt. So, obviously, it has a lower profile and less puffed-up status, but works just as hard, as well as being prettier. Joking! Well, kinda. Anyway. This blouse is mine, and came from & Other Stories a year or so ago. It is as useful as any white shirt, because a shot of cream lace prettifies anything you put it with, from a pair of jeans to – today – a vintage pencil skirt.

Related: How to wear: the boat neckline | Jess Cartner-Morley

From grubby trousers to glamorous coats, members of the Guardian style team have very different ways of getting comfy …

My most comfortable item of clothing is an absolutely disgusting old pair of grey jogging bottoms that are threadbare and slightly see-through. They are beyond comfy, light and excellent for dealing with baby spillages and dirty bathrooms. I will be genuinely sad when they finally disintegrate in some embarrassing way (crotch or bum area first). I would never wear them outside the house, because they are frankly obscene. Except one time when I took out the bins and got a startled look from our upstairs neighbour.

Your last dressy night in a while is not the time to buy something new, so wear the party heels you already own

How likely are you, on a scale of one to five, with one being very likely and five being don’t be utterly ridiculous, to be wearing high-heeled sandals to see in the new year? I’m reading a solid three. I can work with that.

Here are a few reasons why you should consider wearing shoes like this for New Year’s Eve. One: after this, it’s January. This is it, people. Come midnight, it’s all over. The festive spirit will evaporate, like Cinderella’s carriage. Wear those glass slippers while you can. This is not about a dress code, it’s about a ritual. You are going to be in boots and jeans for January (and yoga leggings and running trainers: that’s the plan, anyway). New Year’s Eve is to January what Shrove Tuesday is to lent. Eat up all the glamour, while you still can.

Related: How to wear: the boat neckline | Jess Cartner-Morley

The chain that democratised British fashion has lost out to Instagram and online retailers

2018 was not a vintage year for fashion. The crisis-hit House of Fraser and an embattled Marks & Spencer made headlines, as did a rising tally of planned store closures, and accompanying job losses, deemed necessary in a turnaround plan for New Look. The Orla Kiely brand, famed for its geometric prints, went into liquidation in September, while Dolce & Gabbana ends the year under serious pressure, having been dropped by important retailers after a racism scandal shipwrecked a fashion show planned in China.

But the most significant downfall to impact on the culture of fashion is that of a store still very much open for business. The undoing of Philip Green, and by association Topshop, is a watershed moment for British high street fashion.