Crime author and Prime Suspect creator Lynda La Plante says 'no way' she would retire as she approaches 80

Lynda La Plante turns 80 next year – but she’s calling this decade “the new 50s”.

“There’s this slew of incredibly old actresses treading the boards, there’s the wonderful Glenda Jackson, 85, doing King Lear, and you think, are we the new 50s? There’s Amanda Barrie, 86 going to India with Miriam Margolyes, 80 [for The Real Marigold Hotel series].

“The wonderful actress from Widows, Ann Mitchell, going off to Hungary to make a movie and she’s 82! And it’s like, we’re the new 50s.”

The bestselling crime author of no less than 40 novels – as well as the hit TV series Prime Suspect starring Dame Helen Mirren – says there’s “no way” she would retire.

“I’ll continue to do it until I drop off the earth. Because I’m still learning new things all the time. I love it, it’s very exciting, it occupies my brain.”

“All my friends are the same,” she adds. “I think mental health is absolutely connected to my work. It keeps you very mentally alert.”

And physically, she feels great too. “I’m one of those who gets up and about, I get up at 6am every morning,” she says – despite suffering from insomnia sometimes (the middle of the night is often when she “works the plot out” for her novels).

The 79-year-old’s latest book, Vanished, the third in the Jack Warr detective series, starts off “a rather irritable investigation of an eccentric lady” and ends up being a murder investigation and hunt for a suspect who appears to vanish into thin air.

A certain amount of solitude is all part and parcel of being a novelist, but for La Plante, that doesn’t mean silence: “When I’m working, I’m energised, talking, being the characters, I’m laughing, crying, I act it out. Sometimes people have walked in and been quite shocked.”

The process of writing can bring up surprising, and sometimes painful, parts of her own life. “You use things in your own life, and you suddenly realise you’re writing a little section or segment of your life that you hadn’t paid much attention to.

“Like an ectopic pregnancy suddenly appears in the new novel I’m writing, and I remember clearly, I mean, I didn’t know what it was.” La Plante became a mum at 57, after many years of fertility treatments, going through the menopause at 32 and a divorce, when she adopted her son, Lorcan, now 18.

You might think the creation of dark plots, all devised with rigorous real-world research, would take its toll mentally, but La Plante is adamant it doesn’t affect her. “I’m able to lift it with humour,” she says.

Her chosen method of switching off from crime might surprise people. “I watch very odd programmes – like My 600-lb Life [a weight loss show on TLC]. I am an avid watcher. There’s something absolutely exquisite about how they have fought for their lives, and you go through therapy with them,” she says.

When it comes to looking after her own diet, she doesn’t want to waste lots of time cooking. “One of the biggest things in my life is finding the chicken that cooks itself in the bag,” she says, laughing. “I try to eat one good meal a day, I’m obsessed with green beans, I eat a lot of green beans.”

Walking her enormous dog Hugo, a Borzoi, is her only form of exercise and brings her a huge amount of happiness. But his battle for his life has dominated La Plante’s for the past year – he’s been in and our of surgery for a punctured lung after swallowing pampas grass.

“I cannot believe this dog has created so much emotion in me, so many tears, so many prayers. All the dogs I’ve had in my life, nothing compares to this one creature – he’s so gentle, and so loving,” she says. “And now he’s eating like a starving donkey but he’s back.”

Vanished by Lynda La Plante is published by Zaffre, priced £18.99 in hardback. Available now.