Nick Dear (1955-) wrote six adaptations for Poirot between 2003 and 2013. Outside of Poirot, he is known as a BAFTA-winning script writer (for Persuasion, an adaptation of Jane Austen's novel, in 1995). He has also written biographical TV movies on Byron and Beethoven. In 2011, he adapted Mary Shelley's Frankenstein for the stage, directed by Danny Boyle and starring Benedict Cumberbatch and Johnny Lee Miller (the two Sherlocks!). In other words, he was no stranger to literary adaptations when he was asked to adapt Christie's novels.
"I was first approached to do it in 2002 I think. (...) I couldn't say Agatha Christie was very high on my reading list. I thought I was much too much of an intellectual for that. I'm now prepared to accept that I might have been too much of a snob because after a dozen years of being associated with the shows, because I have written six of them now for ITV, I think it's very classy entertainment and I'm pleased to be associated with it." (Huffington Post interview, 2013)
"Nobody ever grieves for a minute in Christie; 10 seconds of grief, then it's onto the next murder. What we've done with them in the last 10 years is make them rather darker, existentially bleaker, and have Poirot faced sometimes with very difficult moral choices" (Huffington Post interview, 2013)