Last night, I watched the new adaptation of Agatha Christie's 1952 Poirot novel Mrs. McGinty's Dead . As always, David Suchet's performance as the little Belgian detective was excellent, and, although she is by no means an adequate replacement for the Poirot family of Hugh Fraser, Pauline Moran and Philip Jackson, I am warming to Zoë Wanamaker's Ariadne Oliver.

And yet…

Why am I unsatisfied?

One of the most attractive points of the classic Poirot series was the sheer stylishness of the cinematography: the Art Deco ambience, with its strong, clean lines, and period sets shown in meticulous detail. In this latest story, however, the lens seemed to have been smeared with Vaseline (à la Web Planet , a William Hartnell Dr . Who story), and the picture often consisted of talking heads against a fuzzy background. Even worse was the intrusiveness of the direction. Too many shots from odd angles, including through the steering wheel of a car, and modern television directors' predilection for zoom shots. This was particularly galling in the recent adaptation of Bleak House . Some clever clogs director had obviously come across a description of Dickens's prose as being like a camera zooming in from a town to a street to a room. And the result? BANG! goes the camera as it hits the walls of Chesney Wold. SMASH! go the windows as the camera goes hurtling through. Give me the filmed theatre of I, Claudius , in which actors delivered dialogue to create character; the simple but effective Hickson Miss Marple series; or, indeed, the earlier episodes of Poirot , rather than this hyper-active, twitchy, jumpy camerawork for (apparently) audiences with the attention span of flies.

The script itself was far more faithful to the book than the preceding series, which offered a sour and over-dramatic After the Funeral , an asymmetrical travesty of Cards on the Table , a brash and soulless Waughian vulgarisation of The Mystery of the Blue Train , and a disastrous adaptation of Taken at the Flood which, by moving it from the immediate post-WWII period to the mid-1930s, completely missed the point of the novel. In Mrs. McGinty's Dead , the main events of the book were presented on screen—and in that lies the trouble.

The programme was not so much an adaptation of the story as a display of its bare bones. The essence of the work was gone. Christie's depiction of an English village in the early years of the welfare society was irrelevant, since the story, like nearly all the Suchet adaptations, had been backdated to the mid-1930s. So many of those small but telling details—a bored Poirot's regret that one could only eat so many times a day; the splendid comedy of the chaotic boarding-house; the ingratitude of James Bentley—which brought the book to life were gone. In their place was a determined effort to get through the story as quickly as possible, without worrying about unnecessary things like character or atmosphere, which could be achieved by making the village look as bleak and inhospitable as possible, and all the characters as unhappy as possible. The Summerhayes, who in the book embodied a cheerfully haphazard determination to battle through and make things work, as Britons did during and after WWII, were now beset with marital difficulties. Shelagh Rendell, who was cool and intelligent in the novel, became a neurotic who survived only on medications. Most worrying of all was Poirot's tacit condonation of euthanasia—a sentiment which Christie, in her Sad Cypress , strongly opposed.

The tone of the whole piece was wrong. Since the re-vamped season of 2003, when a completely new production team took control of the series, the programmes have all been resolutely downbeat. This worked splendidly for the first season of Five Little Pigs , The Hollow , and Sad Cypress , which are among Christie's most character-driven novels. Even then, however, I had grave reservations about Death on the Nile , which lacked the warmth and wit of either the novel or the Peter Ustinov film, and replaced the sunny splendour and ancient mysteries of Egypt with washed-out grainy film noir flashbacks. Certainly the dark mood is not suited to the novels of the early 1950s, which, in their emphasis on detection and plotting over character, are something of a return to the works of the 1930s.

Much of this has, I think, to do with the estate's determination to present Agatha Christie (judging by “The Unicorn and the Wasp”, a David Tennant Dr . Who farce—think The Secret of Chimneys meets The Fly ) as the equal of Shakespeare or Dickens. Christie was great, we are told, not because she was a brilliant detective writer; instead, she had a peerless understanding of human nature because had suffered. Certainly the current HarperCollins editions of Christie books are marketed as grim and dark and adult (and with the text size blown up to ludicrous proportions to give the books the heft of a Minette Walters blockbuster). In short, Agatha Christie is being pushed as the precursor to PD James—which she was not (that would be Nicholas Blake).

Both are Anglican detective writers who had very unhappy experiences—James's mother and husband both committed suicide, while Christie famously disappeared after her mother died and her husband abandoned her. And yet what a moral and philosophical gulf there is between them. James is remorselessly dour and angst-ridden, in stark contrast to Christie's shrewd commonsense, sanity and robust cheerfulness.

Christie acknowledged the dark side of human nature, and, particularly in her later books, the problem of evil. At the same time, her books are humane and optimistic in a way that James's downbeat works simply are not.

Christie was also a universalist. She was as much a shrewd observer of mankind as Miss Marple herself, and her novels are full of observant asides on the constancy of human nature in a changing Britain . Her characters may not be particularly deeply drawn (with the exception of those in her works of the late 1930s and 1940s), but they live . They are vivid depictions of something more than types, whom the reader recognises. There is nothing here of PD James's increasingly clumsy handling of characterisation, which, in her works of the last two decades, consists of large slabs of back-story (invariably some dismal personal tragedy) attached to not very interesting or memorable people.

And yet there is a grain of truth in this. Christie's books have survived not because of the ingenuity of the plotting, but because of the writer's character. Christie's detective stories are character-driven in a way that the works of John Dickson Carr or Ellery Queen or John Rhode simply are not, and her novels have more ingenuity and structure than the novels of Gladys Mitchell or Margery Allingham. In short, at her best, everything in Christie is in balance, as perfectly proportioned as Poirot himself could desire.

By stripping the warmth and humanity from these adaptations, by presenting Poirot's world as an unflaggingly dour and depressing one, the producers have been untrue to the spirit of Christies past.

And yet why should the producers feel the need to do so? Why should Christie's estate prefer to market her as a pessimistic Balzac rather than a brilliant detective writer who was also, like all truly human writers, an optimist? Why do modern audiences feel it is more adult and mature to be unhappy (which is both an adolescent emotion, and, since despair is passive, a lazy one) than to be happy or hopeful (which takes courage)? Why is it more respectable to deny life than to celebrate it? And what does this say about the detective story itself?

These are questions for next time, however…