Watching the popular and long-running Midsomer Murders TV series it is tempting to assume its creator hails from the same cosy, middle-class world. In fact, Caroline Graham, who wrote the seven novels featuring Chief Inspector Barnaby on which the TV series is based, had a far less privileged upbringing.

Her mother died when she was six and her father remarried when she was 13, resulting in what she describes as “a difficult childhood”.

She said: “I failed my 11-plus but was fortunate enough to win a place at the high school at 13, where I had the most wonderful English teacher who encouraged me to write.”

She quit school at 14 to work in a textile factory, doing shift work and earning three shillings a week, but looks back on this with equanimity. “It was time I went to work because I had to contribute. That was how you thought if you were working class. But I knew I wouldn’t stay.”

Three years later she made her escape by enrolling in the Wrens. “I ran away to sea. I went into the recruiting office and looked down the alphabetical list of jobs — administrator, cook, cleaner, driver and spotted ‘writer’ at the bottom.

“I ticked that one and went off to do my training but soon discovered ‘writer’ just meant a clerk.

“I was devastated. I’d thought I was going to be writing a diary or something. Talk about naive.”

She left when she married former husband Michael and gained a place at ballet school in France where they were living. She said: “I have always been a born show-off. I danced for a while, then took some drama lessons. I lost my powerfully strong Nuneaton accent and got jobs in theatre. My husband was marvellously understanding but what with me being never there and gallivanting all over the place, the marriage fell apart.”

The catalyst for her career as a writer came in her late thirties when she went to a talk given by an author at her local library.

She was hugely impressed by Christianna Brand, a crime writer and the creator of Nurse Matilda, later adapted to become the film Nanny McPhee. “She was superb and everything I thought a writer should be. She was wearing brocade, fur, a hat and had a cigarette in a long holder. And she said she would be happy to have a look at our writing so I rushed home, wrote a story and sent it to her.”

An encouraging reply prompted her to enrol on a creative writing course and over the next couple of years, she had success with several radio plays and episodes for 1970s TV soap Crossroads.

Meantime, she had her son, David, now 40 and wrote a romantic novel and two books about BMX bikes, before creating the first Midsomer villages novel, The Killings at Badger’s Drift, in 1987.

Universally good reviews gave her the encouragement to continue with the series, but she could not have imagined that when the books were adapted for TV ten years later it would attract millions of viewers and run for a decade and a half. Wallingford features on TV as Causton, where the police station is in the books, and other Oxfordshire villages have been used as locations for the series over the years. She says the stories were not set in any particular place. At the time she was living in a Suffolk village so she drew on her experience of village life generally, and the production company wanted it to be near the studios at Pinewood. She said: “I have been told that the reason people like the books is because they like the characters.

“Tom Barnaby is a straight, happily- married middle-of-the-road copper. He’s strong but he’s not intensely charismatic or eccentric in any way.”

Caroline’s last book in the series was A Ghost in The Machine in 2004 but she was not sad to say goodbye to Barnaby. “I always planned to write seven and was relieved in some ways when I finished the last book.”

Along the way she managed to cram in an MA in theatre studies at the age of 60 and now, nudging 80, she is studying an Open University course on Shakespeare while writing a novel set in 1890 and La Belle Epoque. Unlike Chief Insp Barnaby, there is nothing middle-of-the-road about the remarkable Caroline Graham.

Caroline Graham will front a Q&A session with fellow crime novelist Ann Granger at the Witney Book Festival on June 17 at 2pm in Langdale Hall. See Bookings, right.