PD James, who has died aged 94, once said she started writing crime fiction as a preparation for a career as a serious novelist but ended doing as much as anyone to elevate the whodunnit to an art form.

Widely regarded as the Queen of crime writing, she spent more than half-a-century charting the career of her poetry-loving policeman Adam Dalgliesh and through him the postwar history of the UK.

She also wrote a memoir and several standalone novels while the Dalgliesh books found a wider audience through a series of ITV adaptations with Roy Marsden in the lead role.

In a 1995 interview with The Paris Review, she said she was "born knowing" she wanted to be a writer and "had an interest in death from an early age". She said: "When I heard, Humpty Dumpty sat on a wall, I thought, Did he fall or was he pushed."

James did not originally intend to become a writer of crime fiction, which she said was "very easy to write badly but difficult to write well". But she told The Paris Review: "Then when the first one worked, I continued, and I came to believe that it is perfectly possible to remain within the constraints and conventions of the genre and be a serious writer, saying something true about men and women and their relationships and the society in which they live."

Born in Oxford, she grew up in Cambridge and left school at 16. She married a doctor in 1941 and had two children, but he returned from the war struggling with his health and unable to work.

She spent 30 years as a civil servant and only published her first novel, Cover Her Face, in 1962 at the age of 42. That launched her on the path to best-selling fame and her books have sold in their millions around the world. Along the way, the Mystery Writers of America gave her a Grand Master Award, the BBC made her a governor and John Major sent her to the House of Lords as Baroness James of Holland Park.

She was a critical ally of the BBC and hit the headlines in 2009 when she famously confronted its then director-general Mark Thompson during an edition of the Radio 4 Today programme about the excessive pay packets given to some of its top executives.

She grilled him as she took the helm as guest editor of the show, telling him it was “really quite extraordinary” that 37 BBC bosses earned more than the Prime Minister.