"I decided I didn't want to be part of the problem, in terms of how I portrayed women to women," the 48-year-old English author of international best seller Me Before You explains over the phone en route from her Essex farmhouse to London.

Jojo, who has a 19-year-old daughter, Saskia, is conscious of the example her female characters set for young women. And beneath their veneer of chick lit, Jojo's books are thought-provoking with a subtle dose of feminism.

Born very premature, Pauline Sara Jo Moyes nearly didn't make it. She was christened in haste, named for her mother's three closest friends. When it became apparent she was going to survive, her parents thought Pauline too big a name for "such a tiny little sparrow of a baby", so she became Jojo (referencing the character in the Beatles' song Get Back) and it stuck.

Jojo grew up an only child in London, a bookworm wrapped up in her own imaginary world.

Despite her city upbringing - her mother was an illustrator and her dad transported fine art, asking clients such as David Hockney to make sketches for his daughter - horse-mad Jojo wanted to be a blacksmith.

As a result, her mother transformed her bedroom into a stable for her 10th birthday, she bought a horse with her own money when she was 14, and National Velvet is still a favourite book. Yet the 157-centimetre blonde had neither the height nor the strength for her chosen trade.

There were other disappointments, too. Her parents split up when she was 12, and she had "lots of complicated relationships" (including an engagement at 17), before she met her husband, journalist Charles Arthur. As well as Saskia, they have two sons, Harry, 16, and Lockie, 12.

Jojo is upfront about the therapy she had in her 30s, which made her examine her patterns of behaviour.

"People divide quite clearly into those who are capable of looking at themselves and those who can't," she says. "When people can't, it's amazing the traps they set themselves, and they walk into the same mistakes again and again and again."

Although she never saw herself as a writer, Jojo fell into journalism and ended up on the news desk at The Independent. She was writing fiction during the day before her night shifts, until the arrival of children prompted her to take up writing full-time.

"I've always been one of those people with half a novel on the go," she explains. "I started having kids, and newsrooms and babies don't mix - not if you want to do it properly - so it gave me the extra push to keep writing."

That push saw her write three books before she finally got the fourth published, in 2002. A further seven novels followed, none of them very successful. ("That's a diplomatic way of putting it," she laughs.)

"I was preparing for it to be over because you can feel your publisher cooling on you," she says. "There's only so long you can be the next big thing without anything actually happening. The advances were dropping dramatically, the attention was getting less and I thought, 'What am I going to do?' "

Things were looking so dire she and her husband started planning to take in lodgers to make extra money.

Then, in 2012, came Me Before You.

The story of young working-class Lou Clark, who is employed as the carer for wealthy quadriplegic Will Traynor, became a New York Times best seller, and has now sold over 12 million copies. The 2016 screen adaptation, also written by Jojo, grossed over $250 million and sent her profile sky-rocketing, generating a surge of interest in her back catalogue.

She now finds her novels in B&Bs and is recognised in public. She's walked the red carpet at film premieres and awards ceremonies, and when she turns up at book signings the room is often crammed with women wearing Lou's famous bumblebee striped tights. Not bad for a book that her husband joked would finally kill her career stone-dead.

"Luckily for me it went the other way - pretty unexpectedly for all of us," Jojo says.

With its appealing lead characters, topical themes of chronic illness and end-of-life choices, and thorny "what would you do?" conundrum, Me Before You was a word-of-mouth hit.

Yet because of her years of struggle, Jojo had little faith her success would last. "Every week I would say, 'Well this has been nice' and wait for it to drop [out of the best-seller list]," she recalls. Even now, Jojo, who's warm and friendly, seems to half-expect it to all end in an instant.

Readers' desire to know what happened next for Lou prompted a sequel, After You, another best seller. Tomorrow, the third instalment in Lou's story, Still Me, is released. "I saw it sort of as a horseshoe shape, in that I brought Lou down - After You is quite a melancholy book in many ways - and then I wanted to bring her up again and take her out punching."

Still Me sees Lou move to New York to start a new life while endeavouring to maintain her relationship with Ambulance Sam in London. A catastrophic change of circumstances forces her to confront who she really is and what she wants.

Jojo says, "Because I knew that Lou was a role model for a lot of young girls, it was really important to me that she found her own happiness, that she found what was going to make her happy independent of a man - independent of a career, even."

Still Me has all the hallmarks of her best writing, especially her deep sense of empathy. She attributes her keen insights into character and relationship dynamics to the fact she hasn't led a straightforward life.

"I didn't sail through my early years," she says, "and I think if you have to deal with a certain amount of stuff it gives you perhaps a slightly more mature view of human nature."

Lou Clark fans should savour Still Me, because her story is now complete. "I hate saying that because I really love writing her, she feels like a friend after all these years, but I don't want people to get tired of her and I feel that this is the natural stopping point."

Meanwhile, Jojo is researching her next book, has film scripts waiting to go into production, and is working on a comedy pilot for American TV.

Like all working parents, she scrambles to fit everything in. Her favourite pastime is getting lost in the woods near her house riding her horse, Brian, but she's so busy she barely gets the chance. Otherwise, her idea of heaven is sitting at home watching TV with her family, dogs at her feet and the fire going.

In retrospect, Jojo is grateful that her success came later in life. "I was dreading my 40s, like most women," she says, "and now I love telling younger women that pretty much everything good that has ever happened to me outside of my family happened in my 40s."

She thinks being a late bloomer has given her a greater appreciation of her success - and more equanimity about its possible passing. "If it all stops tomorrow," she says, "my god, I've had a pretty good run."