"Yeah, there's a lot out there," she agrees, sinking gracefully into the low-slung, 1970s, dusky pink Mario Bellini sofa on the first floor of her Bond Street store (called the Camaleonda, it's one of those iconic sofas you see in Architectural Digest and, naturally, she recently collaborated with Bellini and B&B Italia on a line of sustainable furniture for Salone del Mobile).
There's nothing that Stella loves more than a project, especially if it involves a house and a garden.
"I've never bought a house that wasn't falling apart," she told American Vogue back in 2010, when they featured her remote Georgian pile in 277 acres of Worcestershire that had been reduced to a series of grungy bedsits when she and her now-husband Alasdhair Willis bought it in 2003.
But back to beauty. "To get what I want currently – pure, organic, effective - I have to shop across ranges. Whereas my line is so simple. Just three products". A cleanser, a serum and a moisturiser, all in refillable packaging.
There's no eye cream because she doesn't bother with it and the serum does it all really, she says. McCartney doesn't always use sun cream either.
"The problem is so much of it's terrible for the planet. So then I think, OK, just stay out of the sun. But then it's like f--- it, the sun feels so good, so maybe just for a couple of minutes, just for the Vitamin D. I'll probably end up a very gnarly 80-year-old. Ideally though, I'd rather not be gnarly."
That surprises me because I thought she'd say she'd like to end up like US writer Joan Didion.
At 50, McCartney still retains that effortless cool, slightly boho-but-tailored style that she helped make synonymous with London in the 1990s, but which in part came from her American mother.
Then again, she always looked more groomed than the average London girl. When we meet she's in denim, a blazer and strappy sandals, her distinct russet mane as vivid as ever. There's no nail varnish, artful make-up – more than she normally wears, she says, because she's being photographed. Although she has an identifiable style, it's never been fixed. Her collections often do a volte face – sporty utility one season, romantic the next.
"My problem is I love everything – minimalism, monochrome, colour, glitter..."
Growing up, artifice was on the back burner. The McCartneys split their time between the Sussex farmhouse and Kintyre in Scotland.
In 1969, a Life magazine cover (now framed in one of Stella's loos) fan-fared the case of "The Missing Beatle", having tracked Paul and Linda down on their remote Scottish farmstead.
"I think my childhood in Scotland was where I felt cleanest," Stella says now. "It was so... natural. We were always naked. My parents didn't even wear deodorant and yet they never smelled."
A rare aberration in this clean-living paradigm was the foaming Clarins Cleanser that Linda gave her daughter when she was about 13. "It was everything I now know is bad about skincare… but it was the 1980s". And it set her on a quest for skincare. She might be laid-back, but she diligently tends her skin, which is tanned, but largely unlined, with a distinctly expensive-looking sheen.
Failing to appreciate, as kids do, her mother's low-maintenance approach to beauty, teenage Stella begged Linda to wear make-up.
"In fact I did her make up for her. She was into it, but it wasn't an obvious presence. There's a McCartney rose. We'd grow loads of them and my mum would have it made into essential oils. There were a lot of essential oils.
"I'd also nag her to wear all the fabulous clothes she wore on tour, and her jewellery. She had such beautiful jewellery, but she never really wore it. And now – look at me."
She thrusts out her arms to display... nothing, apart from a tiny gold evil eye bracelet. "I found it on the floor of my dad's house, so if you visited him there and you're missing an evil eye, I've got it."
Her parents inspired everything she does, but now she also leans into her children, aged 11 to 17, listening to their concerns about the planet and looking for solutions.
"Everything I've done – kids' wear, vegan shoes, mushroom leather bags, organic, certified fabrics – has been because I couldn't find it in quite the way I wanted it. There's no other line of beauty that's as clean and luxurious, with all the active ingredients, as this one."
Nor, she could add, with the distribution. Because this time round, she has the backing of LVMH, the luxury behemoth that also owns Celine, Dior, Fendi. Loewe, Louis Vuitton, Tiffany, Loro Piana, Celine... and Sephora, the global chain of beauty stores. Safe to say the new Stella beauty line will reside in appropriate splendour.
Selling a minority stake, in 2020, to LVMH, the world's largest luxury group, was a surprise move. Seventeen months earlier, she'd bought back 50 per cent of her company from the Kering Group, France's other, slightly smaller luxury behemoth (Balenciaga, Gucci, McQueen...), amid speculation that she'd become frustrated.
Like every fashion brand, the pandemic was tough for her business, but even before that, revenue for the year ending in 2019 was around £32 million ($61 million), making her a relative minnow. Small brands don't always get the attention they need to grow in a conglomerate.
"I loved working with Francois-Henri," (Pinault, Kering's chairman and CEO) she says. "But I started to think about all the designers who'd lost their names [after business relationships had turned toxic with business partners] like Jil Sander, and I thought, I'm in a uniquely privileged position of being able to buy back my label, so I should."
At LVMH she's not only plugged into the world's most powerful luxury stable, but has been hired as sustainability advisor to its president, Bernard Arnault.
When she was asked, at the time, whether her appointment was a shiny piece of greenwashing, she responded bouncily: "I hope I can be an agent for change from within, like my mother was." That meant a huge amount of extra credibility for her.
"This business is absolutely not some dilettante joke," she says of her company, becoming so emotional at one point, I think she might cry. "It means so much to me. That's why I get so stressed when we do a new launch. I'm so nervous about this beauty line, but I know my mum would love it and she'd trust it because her daughter did it."
She talks about privilege a lot. Being one of Paul McCartney's children has probably added an extra layer of well-intended complexity to being the offspring of someone famous.
Paul and Linda went to enormous lengths to lead a normal life. Yet they weren't. There was the time, back in the 1980s, when Michael Jackson came for dinner at their farmhouse in East Sussex. Of course she couldn't tell anyone about it at her normal state school the next day.
That duality's always been there. She's very matey with everyone, but her actual friends are Kate Moss, Liv Tyler and Tom Ford, and that can lead people to assume she's faking the charm with everyday folks.
You probably can't win when you're a McCartney and, given what happens to many famous parent's progeny, Paul and Linda did just fine with theirs. Mary, 52, their eldest, is a successful photographer (and sometime cookery writer, like her mother). James, 44, is a musician. Linda's daughter with Joseph Melville See, Heather, 59, whom Paul later adopted, is a potter.
Stella, meanwhile, is an undeniably successful, ground-breaking designer, married to Alasdhair Willis, also a designer (he was creative director at Hunter for a decade before moving to Adidas), also good-looking, also successful.
The couple married on the Isle of Bute in 2003. Madonna and Pierce Brosnan were in attendance. Tom Ford gave them an avenue of trees for their Worcestershire retreat as a wedding present. They've since planted a million trees on that estate, creating their own Eden.
"I was riding my horse there the other morning and living my best life and thinking, all that matters is that I get to do all the things I wish my mum had."
