I am not going to tell you about any of the most exciting things that happened at Paris fashion week. I have nothing to say about Bananarama singing He Was Really Saying Something as a live accompaniment to the glitter-bombed finale of the Sonia Rykiel show. Zero hot takes on fashion’s ongoing love-in with Stranger Things, which saw 15-year-old actor Sadie Sink (Max in the second series) make her catwalk debut for Japanese streetwear label Undercover. I am even going to spare you my first-person account of the hype-gone-wild scrum outside Virgil Abloh’s Off-White show, even though I have a purple bruise on my leg from being knocked to the ground. You will notice from the photos that I have deliberately not picked out the Insta-bait activist-chic slogans at Balenciaga or Christian Dior.

Let’s forget all of that, and focus on what Paris fashion week means for what we are going to wear. There is so much to see at fashion week that this can be obscured, but it is – surely – still kind of the point. Fashion weeks should inform you about whether you need to persevere with socks and sandals (spoiler alert: no) and whether the midi-skirt hemline has sufficient legs to justify buying another one (yes). It should give you a steer on the pieces to dig out of storage (anything in black leather) and the quick-win accessories that will keep your look current (oversized earrings). I am as intrigued by the possible future directions for fashion suggested by flight-of-fancy catwalk and front-row antics as anyone, but I also need to find out whether next season is about a rounded or pointed toe before I buy any more shoes.

Chloé, Hermes and Balenciaga at Paris fashion week. Composite: Rex

It is not about an entire new look for next season. That doesn’t happen any more. Instead, fashion week is about spotting the small shifts you can make to your wardrobe to update it. The fashion industry has all but given up on the twice-yearly flip between opposing themes. That thing where spring/summer is all futuristic metallic sportswear and then autumn/winter is wall-to-wall ladylike pastel tailoring? Over. This is good, obviously, for reasons of sustainability and of us having better things to do than redesign our look from scratch every six months, but it can make spotting the changes trickier, because they aren’t always staring you in the face.

Paris fashion week, more than any of the other cities, has a direct impact on what we wear. It comes at the end of fashion month, so it is where the storylines that have threaded through New York, London and Milan start to come together as a plot for the next season. Also, that how-to-look-like-a-French-girl thing is never not mental clickbait, if we are honest with ourselves. A key internal cog shifted in Paris this week, which will soon reverberate through the high street. The departure of Phoebe Philo from Céline has removed a persuasive voice pushing for sculptural, quiet-but-interesting, aesthetically-daring-but-not-skin-baring clothes. Without Philo, what chic looks like has become a little more hard-edged.

Stella McCartney – grey suit under grey coat. Photograph: Getty

Former Saint Laurent creative director Hedi Slimane is not back in town yet – his first collection for Céline will be next season (a placeholder collection by the in-house design team was shown this week) – but his impact could already be felt. Rather than the sweet, pouty city of Françoise Hardy, Slimane’s Paris has always been the darker, seedier Paris of Helmut Newton, and this version was in the ascendancy this week. At Givenchy, the British designer Clare Waight Keller’s second season had more attitude and more edge than her debut and was stronger for it. (She said she was thinking about Berlin, as well as Paris.)

It is a good thing for fashion, this shift, because while Philo’s Céline was great, the inevitable copies were not. They tended toward an anaemic take on wonky tailoring. Now we are headed toward a crisper, grittier version of Paris chic. During Slimane’s years at Saint Laurent, his catwalks were all teeny-tiny slip dresses but the boutiques were full of perfect, sharp-shouldered blazers. His imminent return brings with it the straight-down-the-line blazer as a key piece. There were trousersuits layered under tailored coats at Stella McCartney, brightly coloured blazers over contrasting knits at Balenciaga, check blazers with longline skirts at Christian Dior.

The death of Azzedine Alaïa last year is also shaping this year’s look. The Yohji Yamamoto collection on Friday night was a direct homage to the French-Tunisian maverick, but his motifs were all over the collections: in double-breasted military-tailored coats, in the return of the black leather skirt. There was a longline black leather skirt at Givenchy, worn with a fuzzy oversize knit, and another at Hermes, where a buttoned black blouse was neatly tucked in. A longline belted dress at Hermes was another black leather standout.

Trenchcoats – a classic Parisian trope, and in the ether because of the changing of the guard at Burberry (Christopher Bailey is about to be replaced by Riccardo Tisci) – are a key part of the look of 2018. That means a trench isn’t necessarily something you just throw on when it looks like rain: it can be a dress, as it was at Altuzarra.

Saint Laurent, Givenchy and Christian Dior during Paris fashion week. Composite: Rex

Shoulder robing is basically over (blame Melania) and coats come firmly belted. Givenchy opened with gaudy fake furs, tightly cinched. Emanuelle Alt, the editor of French Vogue, has been wearing her blanket coat with a thick belt at the waist. The silhouette is still overwhelmingly covered up: I am choosing to ignore Saint Laurent’s leather hotpants, and spotlight its long column dresses, also seen at Dries Van Noten, instead. The multi-layers at the neck that were a thing a couple of years ago – a blazer over a shirt over a poloneck – are now happening at the other end of your outfit. A skirt with trailing ties flapping around a pair of slouch boots would have looked messy a year ago, but now that it is on the catwalk at Loewe and at Chloé, it looks like considered, on-point chic.

By the time Isabel Marant opened with Dolly Parton singing Jolene, the western trend was unignorable. Pointed collars, saloon-door curves on shirts and cone-heeled, cowboy-shaped mid-calf boots are this season’s most instantly recognisable trend. There is something slightly comic about the western aesthetic, at least as seen on a catwalk in 2018, that feels like fashion having a sly dig at the absurdity of Trump’s America. Or maybe not. Maybe it doesn’t matter either way. As long as I get my hands on those boots.