LYNDA La Plante is in fine form today, relaxing in the beautiful garden of her grand 19th Century Surrey home, regaling me with colourful stories from her life and career. Peppering her anecdotes with entertaining accents and characterisations, the bestselling novelist and award-winning creator of Prime Suspect is looking forward to the release of the movie adaptation of Widows, her female heist TV series which is now celebrating its 35th anniversary. She is clearly in a good place.

La Plante, 75, is currently debating what to wear on the red carpet at the premiere of Widows, directed by Steve McQueen (12 Years A Slave) and featuring a stellar cast, including Viola Davis, Colin Farrell and Liam Neeson. The story sees the widows of four armed robbers, killed in a failed heist, step up to finish the job.

La Plante met McQueen at Buckingham Palace, during a gathering of actors who'd attended the Royal Academy of Dramatic Art (where the Liverpool-born writer studied acting). "He said he'd been a fan of mine since he was 13 and wanted to make a movie of Widows. He said he'd been obsessed with it. Obviously, there's your Oscar-winner for 12 Years A Slave, so I said, 'Of course!'"

The film, set in Chicago, is due for release in November. With a screenplay co-written by McQueen and Gillian Flynn of Gone Girl fame, there's bound to be a buzz around the movie.

"Steve has updated it to the present day in Chicago. We had a few meetings and looked at the script. He was lovely. I sent notes. A lot of it was me directing him towards the behaviour of the women, rather than anything else. He was like a sponge. He wanted to know where the women came from, how I'd met them, where I got them from."

La Plante's original series and novel (written after the TV series) was classically British, set in London and featuring tough women who had enjoyed the spoils of their husbands' robberies.

Ann Mitchell played the original female lead Dolly Rawlins, and has a cameo role in the film, as well as voicing the new audio book, while La Plante has dedicated the updated novel to the actress.

The success of Widows effectively curtailed La Plante's acting career as she turned to full-time writing, both for TV (Prime Suspect, Trial And Retribution, The Commander, Above Suspicion), producing more than 170 hours of international television, as well as a succession of best-selling novels. She has attended post-mortems, been to mortuaries, befriended detectives and forensic scientists and interviewed prisoners during the course of her research, and in 2013 became the first non-scientist to be awarded an honorary fellowship by the Forensic Science Society.

Her current ebullience is a far cry from her mood last year, when she fell out with ITV executives over the TV adaptation of her Prime Suspect prequel, Prime Suspect 1973, featuring the young WPC Jane Tennison (played by Stefanie Martini).

"I've never been treated so rudely," she says. "The rage syndrome is hard to deal with when you are insulted at every level, when every actor you bring in is dismissed, every director you suggest isn't even considered. I hated it. I just had to walk away to take the stress out of my life."

She has decided to counter her setbacks with success. As well as the forthcoming Widows movie, she also has an American TV thriller series in the pipeline and another early Jane Tennison novel, Murder Mile, out in August.

She has also had other knock-backs to face. She says her sight has deteriorated since a cataracts operation in January. "It's a nightmare," she says. She has seen seven eye specialists to date, she says, but to no avail. "I can only work on the computer for maybe ten minutes and then the eyes weep. It's like I'm underwater all the time. Television is blurred and I have to wear heavy reading glasses if I want to read something, or I use a magnifying glass."

Despite the knock-backs, La Plante remains positive and has no intention of retiring at any time soon. Her adopted son Lorcan, who is nearly 15, is now a "nightmare" teenager, she jokingly laments (she clearly adores him).

And her long-distance romance with a banker in New York has ended. "I got dumped," she whispers. "We really had nothing in common. It fizzled, you might say." She's laughing now. "I can't see many advantages to having a partner, truthfully," she observes wryly. "But if a Clark Gable came along, now there's a possibility."

Widows by Lynda La Plante (Zaffre, £7.99)