It was while she was married to Archie Christie that Agatha Christie, née Miller, wrote and published her first novel, The Mysterious Affair at Styles. That marriage lasted for less than fourteen years, ending in divorce at about the time of publication of her ninth book, The Mystery of the Blue Train, but her career as a writer of crime fiction continued for a further half-century and a further eighty-five titles (excluding the plays she also wrote). Having become known to a vast reading public as Agatha Christie, the author continued to use that name for professional purposes throughout the rest of her life, although privately she became Mrs Max Mallowan soon after her divorce from Christie.

It takes Laura Thompson more than 350 pages to get as far as that, so one must acknowledge that her Agatha Christie is incredibly detailed. She claims that Agatha’s powers declined as her popularity increased. ‘After 1950’, Thompson tells us, ‘she wrote a handful of brilliant and unusual books –