How is it possible to say something new about Agatha Christie, the world’s best-selling novelist, whose life and work have been dissected endlessly over the course of a century? It was a question that crossed my mind when I embarked upon my research for Agatha Christie’s Poirot, a book that tells the story of her most famous creation, the titular Belgian detective. I soon had an answer.

While Christie has been the subject of excellent biographies, wide-ranging scholarly analysis, and popular discussion, I felt that there was more to say about the relationship between the author and her protagonist. I wanted to examine the life of Poirot beyond the words and mysteries that she wrote for him.

I also wanted to see how Poirot has survived without her. Whether Christie liked it or not, Poirot became an entity that took on a life beyond the control of his creator, and so, while their stories were inevitably linked, they also moved in different directions at key points.

“Reluctant Affection”

Several biographers and historians have sorted through many of the same documents that I had available to me, but when viewed with these new questions in mind, they suddenly took on a new life, and there were stories to tell that had not been relevant before.

For example, in 1938, Christie introduced a newspaper serialization by asking, “Why did I ever invent this detestable, bombastic, tiresome little creature?,” before acknowledging a “reluctant affection” for him. Private documentation and correspondence reveal that such a claim underplayed her true feelings, as during this period she would intervene to ensure that Poirot was not treated carelessly by others wanting to use the character on radio, stage, or screen, indicating her affection was much more than “reluctant” as she dismissed even potentially lucrative Poirot projects.

Crucially, Poirot’s story extends beyond Agatha Christie herself, who died in 1976. Archive visits, new interviews, and other contemporary documents suddenly breathe new life into this history of a century of Poirot, whether Christie was directly involved or not. Even events in more recent history have new stories to tell, as revealed when a chance discovery of an outline for a Poirot television series in the early 1980s provided the missing link in tracing the development of the long-running television series starring David Suchet. These adaptations have a considerable legacy, including the hugely successful novels within novels Magpie Murders and Moonflower Murders, by Anthony Horowitz, one of the key writers on the Poirot series who put his Christie knowledge to good use.

Since Suchet hung up his mustache, in 2013, there have been two new major depictions of Hercule Poirot on-screen, as well as newly written mysteries in print (by Sophie Hannah), and as the character continues to appear in more projects, so the story of Agatha Christie’s most famous detective expands and evolves.

Mark Aldridge is a professor at Solent University, Southampton, and the author of Agatha Christie on Screen. His latest book, Agatha Christie’s Poirot: The Greatest Detective in the World, is out now from HarperCollins