Miss Marple and her country-house set sleepwalk through an Agatha Christie travestyThe action had been brought forward from the mid-20s to the mid-50s. Most of the characters had been either renamed or invented. The plot had been largely reworked, with both motive and murderer entirely different. Even the detective was not the same, with Miss Marple being helicoptered in to solve a case in which she had never appeared. But apart from all this, Agatha Christie's Marple: The Secrets of Chimneys (ITV1) was a faithful interpretation of the original story.I know that country-house dramas are this year's big TV must-have and that the producers are running out of stories with which to keep the lucrative Marple franchise on the road, but quite why they felt the need to alter everything so dramatically wasn't clear. The original story – about the intrigues concerning the Herzoslovakian succession – was no more improbable than the one the scriptwriters dreamt up involving an Austrian count, a missing diamond and a secret passage.It's as if everyone involved with the series has lost confidence in the brand and reckons all the punters will stomach now is some whimsy Christie pastiche. The original Marple books weren't that demanding, but they had rather more bite than this.In Julia McKenzie, we have a Marple who gives few signs of consciousness. She sprang to life in the last 10 minutes to deliver the astonishing explanation that the gunshot was not a gunshot but a firework, and that the Marquis of Caterham had both hidden the diamond and accidentally killed the maid 23 years earlier while she was trying to stop him discovering that his wife, who was now dead, had been having an affair with a bloke in an orchestra who now turned out to be the Austrian count who was actually the real father of the marquis's daughter, Virginia. Phew. ...