“I feel like I’ve aged about a thousand years in the last six months,” said Alexa Chung backstage after her second London fashion week show.

The progression from being a model and muse to designing capsule collections and, as of last year, to staging fully fledged catwalk shows has been “unbelievably intense. The behind-the-scenes mechanics of running a business are insane. Which is maybe why this is harder and less frivolous and kooky. Things are a bit less of a laugh these days.”

Facebook Twitter Pinterest Alexa Chung with two models backstage. Photograph: Jamie Baker

There was not a Peter Pan collar or a ballerina pump to be seen at Chung’s second catwalk outing. The first model wore a black patent safari jacket over a black rollneck, with opaque tights layered under black cropped trousers. Tightly belted trenchcoats came with long Tom Baker-era Dr Who scarves, and the puff sleeves of frill-neck Laura Ashley-vibe dresses were layered over thermal-style underlayers, the sleeves pulled down over the knuckles.

Facebook Twitter Pinterest Models backstage at Alexa Chung. Photograph: Jamie Baker

“I wanted to go a bit darker and a bit more nuanced,” said Chung. “It’s how to dress for a crisis. Or how to dress yourself out of a crisis, perhaps. There’s always been a darkness, a kind of emo, in what I do – and more so as I get more grown up. This season I wanted to focus on that.”

Chung told the Oxford Union last year that in the days when she was a front-row fixture at fashion week and Mulberry named a handbag after her, she “felt like I was the Manic Pixie Dream Girl of fashion”. The term was invented by film critic Nathan Rabin to describe a female character who “exists solely in the fevered imaginations of sensitive writer-directors to teach broodingly soulful young men to embrace life and its infinite mysteries and adventures”. Chung felt her “image was being co-opted” as a stereotype who is “usually ‘quirky’ and ‘fun’ and ultimately unthreatening”. Establishing her own fashion brand in 2017 was “regaining some autonomy over my own narrative”.

“I’ve always been a bit off-grid. I grew up mostly in the middle of fields and I didn’t really interact with London much but, in my head, I always felt really sophisticated,” said Chung after ’Saturdays show, dressed in a jade green tea dress from the collection.

“Like, I was wearing silver eyeshadow to muck out my horse.”

Facebook Twitter Pinterest Alexa Chung at her catwalk show. Photograph: Henry Nicholls/Reuters

This is the kind of detail that pigeonholes Chung as an adorable indie eccentric, but her thinking is more sophisticated. She is interested in how people interact with the zeitgeist when they are cut off from the mainstream. On her moodboard for this season was a photo of women in late 1970s Tokyo wearing prairie dresses. “It’s Americana, but their interpretation of Americana,” she said.

She dreamt up a scenario for this season of an all-female back-to-nature-meets-survivalist West Coast bunker in 1983, the year of her birth. The concrete basement of Universal Music offices in St Pancras, London, was repurposed as a catwalk, garlanded with moss.

Softly dishevelled hair and daubs of dark eye makeup were intended to get across the idea of “someone who is a bit cut off from the outside world and is making up their idea of reality”.

Facebook Twitter Pinterest Backstage at Alexa Chung. Photograph: Jamie Baker

Last year Chung hired a head of e-commerce, Chuan Huang, from Ralph Lauren. The next step in brand expansion will see Chung launch a YouTube channel, hot on the heels of the similarly camera-friendly LFW designer Victoria Beckham. Edwin Bodson, chief executive of Alexachung, said the brand had changed some of its supply chain in order to hit lower price points. “Our ethical standards have not changed,” he added. “The factories we work with are carefully audited.”