HOW many lives has Sam Taylor-Johnson lived in her 52 years on this planet? Over the years she has been a child whose parents walked out on her, a Young British Artist, a wife (twice), a mother (four times), friend to the famous (she shared her 40th birthday with Elton John’s 60th), socialite, drinker, cancer survivor (twice), the older woman (her husband the actor Aaron Taylor-Johnson is 24 years younger than her, much to the slavering interest of tabloid newspapers), film director of both arthouse and blockbuster movies, Londoner, and Los Angelino. And before she married her current husband she was known as Sam Taylor-Wood

She is not, therefore, I think it’s fair to say, lacking in life experience.

"There's a great Joan Didion quote," Taylor-Johnson reminds me, "which is: 'I've lost touch with a lot of people I used to be.'

“And I definitely feel like that. I sometimes look at pictures of myself from different periods and I think, 'Who is that?' And then, sometimes, 'Ooh, I don't like that person.'"

These days Taylor-Johnson and her family spend their time in LA, surrounded by mountains. "I tend to get up super-early and go hiking. I've got three dogs. I go hiking with them for an hour, clear my head, come back, get the kids ready for school and then and try and figure out the day.

"It's very different to London life. London life for me was extremely social and a lot of pressure to always be out seeing people and supporting friends' ventures. In LA we're home bodies. We stay at home and cook and hang out."

But today she is back in the city she lived in for most of her life. It feels a little strange now, she admits. She is beginning to feel like an alien in London.

The reason she is here is work. She has a new film to promote. A Million Little Pieces is a story of addiction and rehabilitation, based on James Frey's controversial book of the same name. It's very much a "passion project" for both her and her husband, who also stars in it.

They wrote it together, raised the money together, and then shot it together, in a mere 20 days, "which was insane," Taylor-Johnson admits. But also, might have helped in the long run. "It feels appropriate to the material,” she suggests. “It became very clear to us that shooting this as a glossy, well-funded story of addiction just didn't feel quite right."

It's a raw story that contains the most horrific cinematic dental sequence since Boys from Brazil and the odd spot of male nude wrestling. But it's not without humour. You get to see Billy Bob Thornton wearing a onesie for a start.

"Oh my God, his whole array of outfits is amazing," she says, laughing. "And every time he'd come out, he'd just look at me and go, 'Right?' 'Yeah, right, I'm not arguing. That's such a powerful statement.'

Her lead actor and husband, meanwhile, gets all the nude shots. "The opening scene where Aaron is dancing naked; that was our first day and Aaron hadn't met a lot of the crew and initially I'd written that as an empty room.

"But then, on the day, I decided to fill it with students at the party. So, he came in completely naked and had to perform in front of all these people he didn't know on day one of the shoot.

“But that really put the flag in the sand. 'This is the movie we're going to make. It's raw and we all have to be in it together.'"

Tell me, I ask, was Aaron a pure diva on set? Did he take advantage of his relationship with his director?

She laughs. "Well, the one thing I'm used to with Aaron is whatever character he's about to play or is playing is the character I live with. So, Ray from Nocturnal Animals [Tom Ford's creepy thriller in which Mr Taylor-Johnson is very convincing as one of the nastiest characters in contemporary cinema], I was really happy to say goodbye when he left the house."

To play James, Taylor-Johnson says, Aaron even went on a road trip with Frey, to meet his family and visit the rehab facility Frey lived in. "He came back and he had a lot of James's mannerisms and habits."

The question is, Sam, does Aaron/James take the rubbish out? "When I ask him."

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Frey's book, it should be said, was something of a succes de scandale. After publication it emerged that Frey's memoir of his own time as an addict contained elements that were more fiction than biography. Appearing on Oprah, Frey ended up receiving a very public dressing down from the host who had been one of his biggest supporters.

But none of that is addressed in Taylor-Johnson's film. "It's not that it doesn't matter," she says when I bring it up. "It's there if anyone wants to read about it. Most of the people I know who have read the book felt the story and the way it was written was so powerful and it affected them in such a deep way that we really just decided to focus on the book. The controversy was something separate. And the film was something new."

Taylor-Johnson read the book when it came out and, she says, it affected her very deeply. You do wonder if she could see echoes of her own story in it. In an interview in the Sunday Times two years ago she revealed that during her first marriage to old Etonian art dealer Jay Jopling there was a time when she was drinking to excess. "I would drink to black out most nights," she revealed. "I would say I was an alcoholic."

It's inevitable to wonder if that fed into the film and her interest in the subject matter. "Yes and no," she says when I bring it up. "The wild years of my art world days are something I went through and came out the other side because I got very sick and so I had to go through a very different recovery having to deal with cancer. So, yes, my understanding is definitely there through experience, as well as the experience of friends and people around me."

Her thirties were tumultuous, certainly. At the age of 29 she was diagnosed with colon cancer. At 33, breast cancer. By 40 she was a divorcee. But then her childhood was too.

The facts of Taylor-Johnson's childhood are rather astonishing. She grew up in Streatham with her parents Geraldine and David and younger sister Ashley. When she was nine, her dad, who was an accountant for the Hell's Angels of all things, left home to travel around the world on his bike. He never returned.

Her mother then married a postman and they all lived in a hippy commune in East Sussex until Taylor-Johnson was 15 when her mother walked out on them all. A few months later Taylor-Johnson spotted her through a window in a nearby house.

There's an element of a Grimm's Fairy Tale in all this, I suggest to her. Did it feel like that? "Sometimes it does. I sometimes do think of the younger, littler me."

She pauses and then tells me a story. "I remember being at a bus stop waiting for my bus to go to school, standing there in the absolute sleeting rain, freezing and I would fantasise about movies and being in the world of them. I'd stand there in my dream world. I'm quite a dreamer. It would be something that I would hold on to.

"I think back to that person standing there in the freezing cold for two hours for a late bus and how lucky I am."

I'm not sure if this is a suggestion that her life has been an act of self-realisation or that she is just astonished that she ever managed to bridge the gap from there to here. Because the gap must have seemed huge.

Film-making was a "fantasy goal,” she accepts. “It’s not that I had an awareness that it was going to be difficult. It just wasn’t on my radar that I could do it.

Instead, she went to art school, where she began to meet the artists who would become the YBAs. She even went out with Jake Chapman for a time. She worked as a dresser at Royal Opera House and even managed a nightclub in Camden, before her art career took off.

When it did, she caught the tail of the YBA moment which gave us Damien Hirst and Tracey Emin and so transformed the art world in London in the mid-1990s.

"It was a real zeitgeist moment," Taylor-Johnson suggests. "A lot of creative minds bubbling to the surface at the same time and all with very different but very strong ideas; from Damien to Tracey to Jake and Dinos to Sarah Lucas. There was no common thread. I think the only connective thread was that we were young and British. I don't think any of us enjoyed being under that banner, especially now that we're all probably MABAs."

Many of her fellow artists from that time - Gary Hume, Emin, the Chapman brothers - remain some of her closest friends, she says.

She was still Sam Taylor-Wood at this point. She was nominated for the Turner Prize in 1998 and majored in video work, often involving celebrities. She famously filmed David Beckham sleeping and got a topless Robert Downey Jr to play Jesus to her Mary in a video pieta that, once you got past the Robert J Downeyness, was actually a potent piece of work about the weight and strain that love requires.

Over the last decade her work has rather disappeared from public view. She admits she doesn't even have a gallery at the moment. But she is still making work and would like to show again.

Still, it is perhaps no surprise that art took second place to life given everything that happened to her in her thirties. She once said that surviving two bouts of cancer and divorce by the age of 40 had given her a core of steel, I remind her. Up to a point, she says.

“Yes, I have a core of steel, but any time I have to go through a hospital door I'm a gibbering wreck. I generally cry every time I see a white coat, even if I'm just going to have my eyes tested.

"The core of steel only really translates when I'm in a work environment, where I'm like: 'You can throw as much shit at me as you like. It's nothing compared to what I've had to face. This is all fun and stupid games."

And it has been thrown at her. Taylor-Johnson made her debut with her highly-acclaimed film about a young John Lennon, Nowhere Boy (the film on which she met her second husband; he was playing Lennon), and then a few years later, she was given the job of directing the big-screen version of EL James's erotic novel-turned cultural phenomenon, Fifty Shades of Grey, with Jamie Dornan and Dakota Johnson in the lead roles.

By all accounts, the experience was a fraught one for its director. On set, James turned out to be very hands on. The two women butted heads constantly during filming.

"It was a tough experience,” Taylor-Johnson acknowledges, “and ... I know I suffered from it and it took me a long time to recover. The hardest thing for a creative person is to be told how to think and how to do things. I had a strong vision and that vision was challenged on a daily basis."

Then, when it finally came out, the film was panned mercilessly. There was a blanket condemnation, I suggest. "Don't tell me. I don't read anything," she says.

The truth is the film didn't deserve all of that condemnation. While by no means a masterpiece, it is an efficient, slick piece of storytelling.

"I think people sometimes blanket panic from the conversations that arise out of something like Fifty Shades of Grey; women's desire and sexuality,” she suggests. “My goal was to have the character played by Dakota usurp the all-great and mighty powerful man who is tempted to control her, and I think that comes across in the film.

"But I think people panic when they have a sense that it's about desire that's not just very straightforward and very vanilla."

It should also be remembered that the movie, despite everything, was a huge success. A Million Little Pieces, is a much smaller thing. It also serves as a reminder of Taylor-Johnson's eye for image-making. And yet, she says, she struggles for work.

"I said to Aaron that I feel like every time I do something, I'm back at ground zero. I still have to fight to get on the general list for movies that I'd quite like to be in the mix for, and it drives me insane. I'll hear about ... I don’t know ... A book that I've loved, and I know I've made the calls and I've tried to get the meetings and then I suddenly hear there's a list of directors on it and I'm nowhere to be found. And, yeah, I really get frustrated.

"The fight to get through the door is as real today as it was when I first started out. A Million Little Pieces is a very small film shot on a shoestring and I had to do that just to remind myself that I was fully capable of making a movie under a lot of pressure outside the machine. And so, yeah, I've got to start gearing up for whatever I do next."

It’s always about the next thing for Taylor-Johnson. She doesn’t like to look back. “I’m always projecting forwards,” she admits. Maybe there’s too much in the past worth forgetting.

“Someone said, ‘what’s it like to turn 50?’ I said, ‘f****** great. I am so lucky.’ I’d like to turn 60, 70, 80, 90 and 100 too. Life is a privilege. I can’t fear age. I have to embrace it, having been through what I’ve been through.”

How many lives has Sam Taylor-Johnson had? Not enough yet. Not enough by any means.

A Million Little Pieces is in cinemas now.