Enid, BBC Four

Eventually he was driven to drink and expelled from the marital home, and was last seen walking dolefully down their leafy Buckinghamshire drive with his belongings crammed into his Army knapsack. He was thenceforth an un-person in the Blyton saga, and she even ensured that his publishing career was terminated.

But whatever her husband’s fate, Enid’s goose was trussed, plucked and boiled with sadistic thoroughness by writer Lindsay Shapero. For the first hour of this 90-minute biopic (part of yet another BBC mini-season, Women We Loved), I was gripped by the cold efficiency of Helena Bonham Carter’s portrayal of the beloved children’s author. Though, post-transmission, she may be beloved a little less (Blyton and daughters, pictured)

With 500 million copies of her 750 books sold worldwide, Blyton is an acknowledged phenomenon, her sales matched only by the scale of her self-regard. “I am the guardian of our children’s morals,” she announced regally to her interviewer on BBC radio. Not only this, but “I seem to understand instinctively what it is that children want from a story.” What she really meant was she lived much of the time in her own imaginary childhood world, and her inner narrative provided her with endless material for her books. Everything was about her.

Her love and empathy for children seemingly knew no bounds, as she diligently toured the country reading her stories to excited groups of them, and spent hours answering sacks of juvenile fan mail. But inside her rambling Home Counties mansion, her personal life resembled an expanse of frozen tundra. When she invited selected young fans to her home for tea and cakes, her own daughters were despatched upstairs and ordered not to intrude. She hired a nurse to prevent the children from interfering with her work, and made it known that she would be available to her children only between 4 and 5pm daily. Even this over-taxed her reserves of empathy. “Incidentally, I’m sending Gillian away to school,” she off-handedly informed the bemused Hugh one day. “Any objections?” Being speechless, he couldn’t think of any.

Having the daughters at all had been more a demonstration of bloody-minded willpower than of maternal instinct, since she had what her gynaecologist described as “the uterus of a 12- or 13-year-old girl”. Very apt for a woman immersed in her own perpetual childhood. The doc proposed hormone treatment. “I’m a very determined woman, Dr Beresford,” she retorted. “If I want a baby I’m jolly well going to have one.”

As the story progressed, I was reminded of Alan Whicker’s interview with billionaire J. Paul Getty, when the great inquisitor suggested to his subject that Getty’s success in business was matched only by his abject failure as a human being. Shapero’s screenplay depicted Blyton as haunted by memories of her wildly idealised father leaving her mother for another woman, prompting Enid to disown mother and siblings and depart for teacher training college. She saw none of them again for 30 years, until her brother Hanly appeared on her doorstep to tell her her mother had died, after a 10 year illness.

An affair with a surgeon, Kenneth Waters (Denis Lawson), seemed to provoke a mild thaw, the implication being that he was a replacement father figure. After she'd become pregnant at 47, the tragedy of losing her unborn son after falling off some steps briefly seemed to penetrate her laminated exterior.

But Enid was a one-act play, ultimately scuppered by the absence of a convincing dramatic arc. A strong cast performed miniature marvels with the script, but they didn't have enough notes to play with - Macfadyen had nowhere to go beyond being the stoical Bloody Nice Bloke, while Lawson was so understanding and uncritical that he began to seem half-witted. Above all, there was no way around the fact that you wanted the central character to be run over by a bus.

Enid repeats on BBC Four on Thursday at 10pm, Friday at 1.25am and Saturday (21 November) at 9pm