It's slightly discombobulating hearing Stella McCartney talk about the challenges of engaging with young people. Can it really be that much of a stretch? Then I remember she's 44.
Like her dad, Paul, there's an eternally youthful Tiggerish-ness to her. Is it the vulnerable cast to those cartoonishly large, occasionally hurt-looking eyes? The quick bounce-back? The apple cheeks? The stylishly sporty silk track pants, worn with men's brogues? "Flat-fronted, elasticated waist, ribbed hems," she enumerates helpfully. "I practically live in them at the moment."
There's a bit of shoulder-robing going on as well, with a tangerine cashmere coat, a lightly tanned, smooth face (does she, doesn't she? I don't know, and it seems rude to ask). Whatever she's doing, it's all working. She looks elegantly modern.
There's also the girlish voice, somewhat at odds with some of her weightier, chewier utterances.
When she tells me about the way she deals with some of her 5- and 9-year-old daughters' more controversial clothes choices ("I say to them, 'Explain to me what is it you like about that'"), she sounds like a head girl trying — and frankly failing — not to be bossy.
We're in a white cube of an office at her headquarters on the outskirts of Notting Hill. It's not until 10 minutes in that I realise her PR is sitting in. He's hidden by a large computer screen. Then again, I'd understand if she never gave another interview at all. There was a time when she seemed to have decided not to. The issues that wind her up — animal welfare, the environment, longevity, the way fashion engages, or doesn't, with young women — are so hard to square with the business in which she's been working, with no small success, for more than 20 years, that she's always going to lay herself open to accusations of hypocrisy. That's before we get to her understandable desire for complete privacy.
But there's a new fragrance to promote. Stella McCartney POP is a sweet, youth-orientated cocktail of sandalwood and tuberose — "a very unfashionable flower, but I like it for that. And it only releases its scent at night." As a matter of fact, Alexander McQueen's creative director, Sarah Burton, and one other major brand we can't currently reveal, have also availed themselves of tuberose in the past few months, for precisely the same reasons.
She's always been good at identifying the zeitgeist. Arguably because she was born into it. But there are plenty of people who miss what's in front of their nose. McCartney gravitated to it like a homing pigeon. She's still there, doing things like fighting to cast the women she thinks represent something other than superficial beauty. Women like Grimes, aka Claire Boucher, the Canadian-born artist-cum-musician-cum-video director, one of the stars of her new perfume campaign.
"I look at Bailey, my 9-year-old, and she's already old beyond her years. She's very aware of advertising. We all are. I feel responsible ... I never want to promote an ad that makes women feel bad about themselves, because when I was young, I never felt rich enough or fashionable enough or good enough. I felt talked-down-to by luxury fashion labels. There was a disconnect. They made me feel we weren't right for each other."
In print, there's a fair chance that such a statement could come across as the Unbearable Pain of Being Famous and Privileged. But eyeball-to-intensely-blue-eyeball, I can tell you it's convincing and likeable. McCartney's heart is in the right place, even if it sometimes trips up on its moral high wires.
She knows, for instance, that producing a perfume instantly raises all kinds of eco-objections, from packaging to harvesting.
"We've simplified the bottle to cut down wastage but, quite honestly, the minute you make anything, you're creating a footprint."
She tells me there's a lot of technologically advanced biomimicry in this scent.
Translation: it comes from a lab rather than fields — in which solution there lies a whole other set of complex pros and cons. But the point is, McCartney has built a luxury fashion brand in her home town, at a time when everyone said it couldn't be done in London; a brand that employs 500 people directly, 250 of those in the capital.
"That's one of the things I'm proudest of — that the people we employ could work anywhere in the world, for any brand, and they choose to be here."
The fact that her company is co-owned by the Kering Group means she has to deliver year-on-year gains. That's not that easy when you refuse to work with fur and leather. She estimates her accessories business could have been five times the size if she'd caved on her principles. But she didn't.
Let's not forget her clothes, because McCartney sells a lot of them, not least because she's always had the knack of being just sufficiently ahead of her customers to be able to inspire rather than alienate them. In the early 90s she gave smart, working women a cool way to dress by eliding Savile Row tailoring with vintage-looking camisoles and dresses: a soft/hard, masculine/feminine matrix that still works today.
But traditional blazers, once a mainstay of her collections, have apparently taken something of a back seat lately. "That's a good thing," she muses. "It's a sign that women don't feel they have to dress like men any more. They can wear a dress to the office without feeling they've suddenly become this sexual creature. They're less dictated-to by the likes of me, and that's great."
These days, she's rarely motivated by trends, which would be "deadly", than finding ways to make clothes more planet- and eco-friendly (quilted coats filled with synthetic wadding rather than down and feathers; committing her label to using only recycled cashmere) and increasingly versatile. "Pockets. I love a pocket. I'm about helping women look as good as possible on the least amount of effort," she says. "I want versatility and comfort. Clothes that can go from the office to anywhere. We're always trying on samples at work. If none of us would wear it, chances are no one else will."
McCartney's own schedule is full-on. "There are some days when the balancing act doesn't feel balanced at all," she says. She's good at empathy and sounding normal, even if the details sometimes give the game away. "Today I couldn't do the school run because we were launching the Team GB kit. But I'll try to do the pick-up this afternoon."
Ah yes. Launching the GB kit. As you do. Typically, McCartney was early to the game of designer gym-wear collaborations. She began working with Adidas 12 years ago — the dark ages of women's sportswear, when you cobbled together a look from what she calls, "crap sneakers and a T-shirt that you'd got free on the front of a magazine. I remember going to the gym and avoiding all eye contact. You didn't want to sweat and you definitely didn't want to bump into anyone you knew on the way home. It bore no relationship to anything you might wear the rest of the time."
McCartney undoubtedly helped change the conversation around workout gear, which, in turn, probably encouraged more women to get active, and has ultimately fed into mainstream fashion.
She herself runs — from the school gate to the office — and remains an active horsewoman (she rides Western-style, in an enormous armchair of a saddle) as well as a fair-weather gardener. "I'm not out in the mud every weekend, but we're good at potatoes, garlic, onions."
As often as they can, the Willis-McCartneys (her husband is Alasdhair Willis, creative director of footwear brand Hunter) pile into their car and head from their double-fronted stuccoed house in Notting Hill towards their home in Warwickshire, an imposing Queen Anne manor with an avenue of trees (a wedding gift from Tom Ford) and its own wood (a joint present from their other guests). "It's important for us as a family to go and sit in the woods sometimes."
She insists she and Willis don't talk shop. "Too busy running the kids to gymnastics or football."
I can't help wondering why she's so keen to take on so many projects — presumably something to do with proving she's worthy of her parents. I think she's also driven by a healthy quota of outrage.
"There are a lot of designers who are very 'f*** you' when it comes to using fur," she says. "If it's wrong to do fur, then they're going to do it.
"But given that there are only about three of us who don't do fur, they're not being very punk. They're just complying with every other fashion house. The fur industry gets to fashion students so young, paying them to use it. But even if you don't care about the millions of animals killed for fashion, it's not sustainable, and it's not modern. Every other industry tries to move forward, apart from the fashion industry."
Whatever your views on fur, it's refreshing to hear someone in the fashion industry publicly saying what they really think. Granted, she has more freedom than other for-hire designers, but it would still be easier for her not to express a single controversial opinion.
If she no longer seems in retreat from the press, that's probably because, with age, she's gained genuine confidence — not the entitled-but-needy cockiness you often see in the offspring of famous parents, but a sense of genuine achievement.
She says she didn't feel a moment's wobble when she turned 40. "Obviously we live in a society where ageing is feared. But, to me, the alternative to getting old isn't that great. I've got friends much older than me, and much younger, and I love that. It means you get to teach as well as learn. I feel attitudes to ageing are starting to change."
She could be right. After all, the demographics are with her — and she does have that nose for the zeitgeist.