The author behind new film My Policeman – starring Harry Styles and Emma Corrin – has revealed she has been “overwhelmed” by the response to its cinematic release.

Novelist Bethan Roberts, who published the book in 2012 after studying at the University of Chichester, said she was “delighted” with the big-screen adaptation of her story.

My Policeman, which begins screening worldwide this week, centres on an ill-fated romantic triangle between policeman Tom (Harry Styles), his wife Marion (Emma Corrin), and male lover Patrick (David Dawson) in 1950s Brighton.

Bethan, who lives in Brighton, said: “The film has been ten years in the making, from script to screen, so the last few weeks knowing it’s actually happening has been overwhelming.

“In many ways Harry Styles is perfect for Tom: he’s handsome, mysterious, and everyone feels like they know him. David Dawson as Patrick is terrific. I admire Emma as an actor – they have great vulnerability coupled with huge strength, qualities they bring to the screen really well.”

The story behind the new film, which also features actors Gina McKee and Rupert Everett, is based on the life of EM Forster and his relationship with a policeman in the 50s.

The couple were in love for 30 years, during a time when homosexuality was illegal, but managed to negotiate a shared relationship with his wife, according to Bethan, who wrote My Policeman from their stories.

The novelist freely admits the book is her favourite work to date – although did not realise how successful it would become.

“Only one per cent of movies that start as a novel get funded, so the journey’s been quite surreal,” she said.

“The film feels quite true to the book and I’m pleased the producers were so careful with the matters raised by the story, and the treatment of LGBTQ+ people in the 1950s.”

Bethan began publishing her books after studying creative writing at the University of Chichester and has since written a series of critically acclaimed novels.

She said: “Studying creative writing at Chichester was hugely influential for me – it gave me belief in myself and the confidence to dream that I could get published.”

The award-winning author is halfway through her next book, the subject of which she is keeping secret for now.

“A writer’s career is a bit of rollercoaster,” Bethan added. “I finished a book when they were filming My Policeman in Brighton, although it’s not yet been published. I will definitely miss the little bit of stardust surrounding the film when it’s all over.”

My Policeman opens in cinemas today (October 21) and is available on Amazon Prime from Friday, November 4.