Murder in mind: Why Agatha Christie was cruel, not cosy

The Queen of Crime was also so appalled by Margaret Rutherford’s comedic version of Miss Marple that she said she was “sick” and “ashamed” of her decision to sell the rights to MGM.

Seeing her sharp-brained sleuth strutting her stuff in Murder at the Gallop (1963) and being trussed up in an admiral’s uniform in Murder Ahoy! (1964) – a film that bore no resemblance to any of her novels – was the final humiliation. “It was my fault,” Christie wrote to her agent. “One does things for money and one is wrong to do so – since one parts with one’s literary integrity.”

Although there have been some celebrated adaptations of her novels – such as the 1957 film Witness for the Prosecution directed by Billy Wilder, the BBC Miss Marple series starring Joan Hickson and some of David Suchet’s Poirot for ITV – there have been many stinkers, too.

A frequent sin committed against Christie is the misguided cosification of her work, enveloping everything in a haze of soft-focus nostalgia. This trend reached its climax during the most recent run of Marples on ITV.

At times, the cast “often perform as if play-acting in a parody of Agatha Christie, dredged from some cultural memory of what her mysteries must encompass”, writes Dr Mark Aldridge in his book Agatha Christie on Screen. “This results in productions that often feel like a barely filtered pastiche.”

The adaptation of Endless Night, broadcast in December 2013, is a case in point. At the end of the episode, Miss Marple (Julia McKenzie) cleverly solves the mystery of Gipsy’s Acre and unmasks the identity of the killer of a rich heiress. There is only one problem: the spinster with the china blue eyes is entirely absent from the 1967 novel.

The injection of Marple into one of Christie’s most unsettling books, narrated in the first person by a working-class man, saps the story of its power. Indeed, according to Aldridge, the whole series does a disservice to the author, “perpetuating the idea that Christie was some generic and old-fashioned mystery writer whose work can only be read or adapted ironically”.

You only have to return to some of her most shocking denouements to realise that Christie was far from a cosy crime writer. One of her murderers is a 12-year-old girl who kills her rich grandfather because he doesn’t want to pay for her ballet lessons.

Another killer is a judge, a man who is supposed to serve as an epitome of justice; and, in one of her best and most controversial stories, it turns out to be the first-person narrator who dunnit.

Agatha Christie may have come across as a shy and retiring upper-class lady, but she was much more than that. It was the contradiction between her public persona and her complex interior life that I took as the starting point for my new novel, A Talent for Murder.

The book is set during the winter of 1926 when Christie disappeared in a real-life mystery worthy of one of her plots. After leaving the Berkshire home she shared with her husband and seven-year-old daughter, she drove to a beauty spot in Surrey where she abandoned her car.

Ten days later – after a highly publicised manhunt – she was finally discovered at a hotel in Harrogate. “Although Mrs Christie may present herself as a normal wife and mother, nothing out of the ordinary,” a character in A Talent for Murder says about her, “dig under the surface and I guarantee you will find someone much darker and altogether more interesting.”

Christie was fascinated by the intricacies of human nature, particularly man’s capacity for evil. One of her favourite phrases was “Old sins cast long shadows”, and she was expert at examining the devastating consequences of greed and desire.

At last, it seems Christie’s darker side is being explored. Later this year we will see new feature films of Murder on the Orient Express (directed by and starring Kenneth Branagh as Poirot) and Crooked House.

After the success of Sarah Phelps’s hard-hitting adaptations of And Then There Were None and The Witness for the Prosecution, the BBC has commissioned seven follow-up dramas. One of the most intriguing of these is The ABC Murders, the same source material for The Alphabet Murders, the film that Christie was warned not to watch.

With these more faithful adaptations, perhaps the ghosts of Carry On Poirot and a twisting Miss Marple might finally be laid to rest.

Andrew Wilson's A Talent for Murder is available from the RT Bookshop now