When she wrote the part of Clarissa in Spider’s Web for the film star Margaret Lockwood, she also, unasked, created a role for Lockwood’s daughter.
When she adapted four of her Poirot novels for the stage she dropped Poirot completely.
The first stage Poirot was Charles Laughton.
She is the only crime novelist to achieve equal and international fame as a dramatist.
She is the only female dramatist ever to have had three plays running simultaneously in London’s West End.
She wrote over 30 plays, of which the most famous, The Mousetrap, is the longest running play in the world, having debuted in 1952.
WHAT HAPPENED TO AGATHA CHRISTIE SERIES
At the Bouchercon World Mystery Convention in May 2000 she was named Mystery Writer of the Century and the Poirot books Mystery Series of the Century.
Christie considered retiring at the age of seventy-five, but her books were selling so well that she decided to keep writing for at least another five years, and wound up writing up until about a year before she passed away at age eighty-six.
When he died, Hercule Poirot was given a full-page obituary in The New York Times.
Endless Night is narrated by a young working-class male which she wrote when she was 76.
She wrote her autobiography over a period of 15 years: 1950 - 1965.
She accepted the Presidency of the famous Detection Club in 1958 on the strict understanding that she would never have to make a speech.
Christie donated the proceeds of her Miss Marple short story ‘Sanctuary’ to the Westminster Abbey Appeal Fund.
In 1954 she was the recipient of the first ever Grandmaster Award from the Mystery Writers of America.
She was the first crime writer to have 100,000 copies of ten of her titles published by Penguin on the same day in 1948 - A Penguin Million.
She wrote an entire book over one weekend: Absent in the Spring by Mary Westmacott.
In her 1942 Miss Marple novel The Body in the Library she mentions herself by name.
Three Act Tragedy, published in 1935, became her first title to sell 10,000 copies in its first year.
When Penguin paperbacks were launched in 1935 The Mysterious Affair at Styles was one of the first 10 titles.
The fact that she was the author remained a secret for almost 20 years.
She wrote six semi-autobiographical, bitter-sweet novels under the pseudonym Mary Westmacott.
When she first started writing poetry in her youth, she wrote poems inspired by the commedia dell'arte, and the figures Harlequin and Columbine.
The Murder at the Vicarage was one of the first titles in Collins’ famous Crime Club series.
Miss Marple was inspired by her maternal grandmother and her friends.
She wrote this while in the Canary Islands.
She described The Mystery of the Blue Train as ‘easily the worst book I ever wrote’.
The Murder of Roger Ackroyd was the first Christie novel to be published in France by Editions du Masque in 1927.
Her 1927 title The Big Four was actually a series of short stories reworked into a novel.
She discouraged publishers from having any representation of Poirot on book jackets, although there are a couple of examples, including Poirot Investigates.
With her earnings from the serialisation of The Man in the Brown Suit, she bought a Morris Cowley.
Twice in her life she ‘saw’ Hercule Poirot - once lunching in the Savoy and once on a boat in the Canary Islands.
She is the only crime writer to have created two equally famous and much-loved characters - Hercule Poirot and Miss Marple.
The Mysterious Affair at Styles earned her the princely sum of £25.
As an inexperienced novelist, she capitulated, but she received many letters from acquaintances noting the "coco" spelling and commenting that she was "never a good speller." Christie thought this was "most unfair."
When she published The Mysterious Affair at Styles, she was forced to use the spelling "coco" instead of "cocoa" due to the insistence of an editor.
It was some four years before The Mysterious Affair at Styles was published, having been rejected by six publishers.
She wrote her first detective novel, The Mysterious Affair at Styles, after a bet with her sister, Madge.
The first ever story that she wrote when she was younger was called The House of Beauty, and she wrote it to stave off boredom while in bed recovering from influenza.
These facts were compiled by Agatha Christie experts John Curran and Chris Chan, alongside Agatha Christie Ltd