Her novels have tackled issues ranging from maternal ambivalence to obesity, and the devastating effect of illness on relationships.

Her protagonists are frequently disappointed and dissatisfied with life, and often pretty unpleasant to boot. Yet bestselling American novelist Lionel Shriver is much more likeable and witty than anyone reading her books might expect.

Her most famous and successful novel, We Need To Talk About Kevin, which won the Orange Prize for Fiction in 2005, centres on a mother who - God forbid - dislikes her son. He grows up to be a monster, and the book and subsequent film adaptation starring Tilda Swinton climaxes in a high-school massacre.

There is further bleak outlook in her latest book The Mandibles: A Family, 2029-2047, which is set in the near future and centres on the eponymous family, each of whom is waiting for an inheritance from 97-year-old patriarch Douglas, which soon turns to ash when soaring national debt puts the dollar in meltdown.

It's a world where jobs are now taken by robots, water is running out and self-driving cars rule the roads, and Mexico is closing borders to desperate Americans wanting to flee the economic collapse. The story follows members of the family as they struggle to adapt to this unrecognisable realm.

She may feel pessimistic about the future, but Shriver, 59, is nowhere near as cheerless as her predictions. She's a straight-talker, with a dry sense of humour that ripples through her novels.

The idea for the latest one was sparked when she worked out that if she lasted as long as her paternal grandfather, she'd live to 2053.

"I found that horrifying," she says flatly. "It's partly to do with population, because it's about mid-century that we're supposed to peak, and I associate that with catastrophe. I'm anxious that we can't support 50% more people than we have now, in that amount of time.

"We are likely to run short of fresh water once we cross about nine billion people. These are not my own personal 'weirdo' anxieties, they are the anxieties of my time."

While she may dread living that long, Shriver is an exercise fanatic who goes to great lengths to take care of her wellbeing.

"I have a variety of routines, but I've been like that since I was 14. It's a regular part of my day and if it ever gets squeezed out, I'm very resentful," she says. "I don't know whether you call that an addiction, but it is a part of my life that I installed very early on and it's served its purposes."

She's had to cut back on running though, due to knee problems. She now does interval training, and plays lots of tennis in the summer.

"It gives me the illusion of being in control. It keeps my energy up, and means I can eat and drink a little more, and makes it easier to sleep."

It's not about trying to live as long as possible, but Shriver is conscious of staying well in older age.

"With decrepitude comes a sense of weakness, powerlessness, fear of being prey and being sidelined, and maybe out of your mind. It makes dying sound great!

"My personal biggest fear keeps changing but at the moment, it would be some physical and/or mental incapacity, but that balances with a larger fear of civil breakdown."

Shriver, who was born in North Carolina but has lived in Britain for years, still has a US passport and says she still thinks of herself as an American. What does she think of the election race?

"It's pretty horrifying," she says wryly. "It's not just Trump being sexist and racist. There's a crudeness to him in a big, broad way that I find really creepy.

"His style is so unattractively arrogant and bombastic and pushy and monomaniacal. You wonder what was it that made him think he was so great?"

She and her husband, American jazz drummer Jeff Williams, have homes in London and Brooklyn, New York, where she returns each summer to visit family and friends.

"The most luxurious side of my life is having a house in London and New York. They are little houses - I call the one in Brooklyn the little dump. Its pokiness is its appeal."

She's glad the media circus that ensued with Kevin didn't happen until she was in her late-40s, when she'd already had six novels published.

"I was getting good critical reception. I was a typical mid-list author, so was always living with an anxiety that whatever I was writing would not be published.

"Kevin was rejected by at least 20 literary agents in the States and 30 publishers in the UK before it was picked up."

Age helped her cope with being thrown into the spotlight, she reflects.

"I had developed a sense of myself that comes with being older and having been round the block. I was much more capable of stepping up to the plate and having to do a lot of appearances on television and radio.

"It's a much more relaxed existence now," she continues. "I'm not swimming in money, but I don't have to worry about it.

"Before Kevin, I had more time to myself. It was easier to get my work done. As I consequence, I sometimes romanticise that period of my life because you could say it was artistically more pure - it was more about the work and less about the promotion of it.

"However, then I have to yank myself back. Professionally, [pre-Kevin] was very frustrating and anxious. I was always on the cusp of oblivion."

The book became a hit in the UK through word of mouth - there were no big publicity junkets. It hit the bestseller list in the US much later, in 2011, when the film adaptation was released.

"I thought the film was good, but I wish it had a little more of my dialogue in it," she reflects. "I thought the casting was great."

Shriver has had mixed commercial success since. Not all her subsequent books have been bestsellers, she points out, but she believes The Mandibles is on a similar scale to Kevin.

"I came across a recent review which said, 'The years during which Lionel Shriver was primarily known as the author of We Need To Talk About Kevin may be coming to an end'. I've waited a long time for somebody to say that."

:: The Mandibles A Family, 2029-2047 by Lionel Shriver, is published by Borough Press, priced £16.99. Available now