BIOGRAPHY: Storyteller: The Life of Roald DahlBy Donald Sturrock, HarperPress, 655pp. £25

IN THE EARLY 1970s, when I was an adolescent, Roald Dahl and his then wife, Patricia Neal, occasionally visited my mother's London house. I knew she was a movie star and had won an Oscar for Hud. I knew he was a writer. I'd read some of his macabre "adult" stories. I knew he also wrote popular books for children, but I hadn't read any of them.

As personalities I found the couple a puzzle: they appeared to me to have swapped national characteristics. Neal, who I knew was American, was distant and wary and seemed English, whereas Dahl, who sounded English even if his parents were Norwegian, was assertive and opinionated and seemed American.

Dahl was enormous – he was 6ft 5in – and his voice was loud. He styled himself a storyteller, not an artist. I liked that. He gave excellent advice on the management of publishers and agents. He had strong political views and naturally inclined towards the underdog. He was apt to pick a fight if he detected pretension, was bored or was intoxicated. His company was invigorating. He had a nasty bite, so it was important to remain alert in his presence. I’d met a lot of writers, so none of this troubled me: all writers were tricky.

Dahl died in 1990. There was an excellent unauthorised biography in 1994 by Jeremy Treglown, and now we’ve the authorised biography. Donald Sturrock’s is written with the family’s approval, and they’ve made a great deal of previously unseen personal material available to him.

The trajectory of Dahl’s gilded yet tragic life went like this: he was born in 1916 in Cardiff, where his father, Harald, was a shipping broker. Four years later his eldest sister, Astri, died of peritonitis: a month later his broken-hearted father followed his favourite daughter to the grave.

Dahl went to Repton, then to Africa with Shell and in 1939 joined the RAF. In September 1940 he crash-landed his Gloster Gladiator in the Western Desert in Libya and suffered terrible head injuries. He recovered sufficiently to fight in the doomed Greek campaign of 1941, after which he was posted to Washington as air attache at the British embassy.

He started to publish and joined the literary agency run by Ann Watkins (the most important decision of his life). In the early 1950s, after years of struggle, he began to sell, to the New Yorker among others, and he married Neal. They settled in Buckinghamshire, and their children, Olivia, Tessa and Theo, followed. Dahl did the mothering; Neal was frequently away, acting and earning.

Sheila St Lawrence – Ann Watkins's successor and the woman who really made Dahl – had been urging him to write for children for years. Spurred now by having his own, Dahl wrote James and the Giant Peach   Charlie and the Chocolate Factory. He'd done it: at last he'd found what he was always destined to do; and now, at this very moment, the calamities began.

First Theo, then four months old, was hit by a cab on a New York street and crushed against a bus (he survived). Second, in November 1962 Olivia, then seven and Dahl’s favourite, died of measles encephalitis. And third, in February 1965, while three months pregnant, Neal suffered terrible brain haemorrhages that left her paralysed and speechless. Dahl ignored medical opinion and initiated a ferocious regime of rehabilitation. Neal gave birth to a healthy daughter, recovered her speech and mobility, and resumed acting.

The marriage, failing before, died completely after her resurrection. Years of marital misery ensued. Dahl eventually found love with his mistress Felicity (Liccy) Crosland. Neal returned to the US.

Dahl and Crosland married in 1983. A period of incredible literary activity followed. Then, in February 1990, Crosland’s daughter Lorina died of an aneurysm. Dahl was already ill, and Lorina’s death finished him. He died in November 1990.

In his lifetime Dahl made enemies and had a reputation for being difficult. The main thrust of the case against him was that he was cruel, ruthless and even sadistic, and that the best example of Dahl at his worst was the way he treated Neal.

For Sturrock, the authorised biographer, Dahl’s standing has to have been a problem: how was he to write an account that avoided hagiography and yet was balanced and fair?

Sturrock’s solution comes in two parts. One, he cites numerous incidences of Dahl behaving badly (and oh my goodness he could be awful). No one could accuse Sturrock of baulking at his subject’s dark side. At the same time he goes to considerable trouble to explain the connection between experience and behaviour that was largely overlooked when Dahl lived – the man’s greater bulk, if you like, that lurked hidden in the ocean below his iceberg’s tip.

There were two key events in Dahl’s life that explain him. One was the mothering he got. Sofie Magdalene had a genius for narrative and made him a storyteller; she encouraged detachment; and she stamped into his psyche the conviction that in a crisis only positive intervention – doing something practical – counted, while intimacy and affection did not.

Dahl’s accident in the Western Desert was the other great event. His brain injuries “materially altered his personality”, inclining “him to creative writing”. In addition, the injuries exacerbated his depressive tendencies and his Nordic hunger for solitude and darkness.

Theo’s accident and Neal’s stroke brought out the best of Dahl: in these crises he was able to intervene, to act – and he did. His daughter Olivia’s death, on the other hand, because no intervention was possible, provoked only despair, and he withdrew. Neal, also grieving, yearned for comfort, but Dahl was too grief-stricken to give it. That and the fact that Neal’s personality was later changed for the worse by her strokes – they made her argumentative and prone to tantrum – were the reasons the marriage ended rather than, as popular opinion had it, because Dahl wanted an improved, younger wife and terminated his marriage in order to get one.

Sturrock’s revisionism won’t convince everyone, but I was persuaded, as well as being grateful for it. It’s more interesting, and more credible, in my opinion to see Dahl as the flawed hero of a gloomy Ingmar Bergman film, which is how he comes across here, than as a pantomime villain.

I’m further grateful to Sturrock for the work he does in support of Dahl’s literary achievement. He shows what a perfectionist Dahl was and how hard won was the pin-sharp clarity of his prose. It’s important to remember and honour this.

I'm grateful finally for the case Sturrock makes for Dahl's trailblazing. When Dahl started James and the Giant Peachjuvenile fiction had no status. Dahl changed that by writing a sequence of masterpieces.

We’re lucky now to live in a golden age of writing for children, but I suspect that without Dahl’s success JK Rowling, Philip Pullman and the others might have found it harder to make the headway they’ve made. Yes, as Sturrock shows, even if he was an awkward so and so, we’ve much to thank Roald Dahl for.

Carlo Gébler is a writer. His short-story collection W9 &Other Liveswill shortly be reissued by the Lagan Press. He teaches at the Oscar Wilde Centre for Irish Writing at Trinity College Dublin