Secret recordings made almost half a century ago have offered a rare insight into one of the most mysterious of mystery writers.

Agatha Christie, who was born 118 years ago today, dictated the tapes on a Grundig Memorette machine in the mid-1960s to help write her autobiography. They lay unnoticed in Christie’s Devon home until her grandson Matthew Prichard stumbled upon the 27 half-hour tapes in a cardboard box.

The autobiography was published posthumously in 1977 but the recordings of Christie’s distinctive voice reveal greater detail of her literary life than the book divulged.

Christie admitted that she had never planned for Miss Marple to become one of her great characters.

Times Archive, 1926: Mrs Christie found - staying at hydro

Following a message received from the local police, Colonel Christie travelled to Harrogate

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“I have now no recollection at all of writing Murder in the Vicarage,” she said. “I don’t even remember why it was that I selected a new character, Miss Marple, to act as a sleuth in the case. Certainly, at the time I had no intension of continuing her for the rest of my natural life.

“I didn’t know then that she would become a rival to Hercule Poirot. People never stop writing me nowadays to suggest that Miss Marple and Hercule Poirot should meet but why should they meet? I’m sure they would not like meeting at all.

“Hercule Poirot, a complete egoist, would not like being taught his business or having suggestions made to him by an elderly spinster lady.”

Only one or two recordings of her voice were previously known to exist, including a 1955 interview for the BBC and a 1974 recording for the Imperial War Museum sound archive in which she recounts her experiences in World War I.

The tapes, however, give no insight into one of the most intriguing parts of her life. In 1926 she disappeared, disguising herself as Mrs Neele, the name of her husband’s mistress, and spending 12 days in Yorkshire while police hunted for her fearing the worst.

While the media embarked on their own nationwide search Christie was secretly performing with a dance band in her Harrogate hotel.

There are some insights into her family life in the tapes and she explains that Miss Marple shared many characteristics with her own grandmother.

Christie said of her grandmother: "Although a completely cheerful person, she always expected the worst of anyone and everything. And with almost frightening accuracy [she was] usually proved right."

Her grandmother would say "I shouldn't be surprised if so-and-so was going on," Christie said. "And although with no grounds for these assertions, that was exactly what was going on."

Christie wrote 80 detective novels mostly featuring Poirot or Marple and it has been suggested that only the Bible and Shakespeare’s canon have outsold an estimated 4 billion copies of her books.

Her play The Mousetrap holds the record for the longest opening run in the world, it began at the Ambassadors Theatre in London on 25 November 1952 and after 23,000 performances is still on in the West End.

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