Agatha Christie’s Seven Dials creator on rites of passage, Broadchurch and Sherlock comparisons, and what you should watch next: ‘It doesn’t feel like we cheated anything’

If you've watched some of the more recent made-for-TV Agatha Christie adaptations over the last five years (and Kenneth Branagh's Poirot movies, depending on your opinion), you'll know that not everybody is out for the…