Storyteller: The Life of Roald Dahl, By Donald Sturrock

Roald Dahl maintained a childlike irreverence in the face (or perhaps because) of life's hardships

Describing himself in his later years as "a geriatric child", Roald Dahl introduced a unique form of subversive energy into the hitherto placid pools of British junior fiction. Often disliked by librarians and regularly missing out on the major book prizes, he declared that, because he was writing exclusively for children, "I don't give a bugger what grown-ups think about it."

While continuing to exclude sexual matters and extreme violence from his texts, he finally allowed that persistent scatology so popular with the young into their reading. When his Big Friendly Giant "whizzpopped" in front of the Queen, children realised that here at last was an author more than willing to share their sense of humour.

But Dahl was more than an irreverent entertainer. Often miserable as a pupil at prestigious boarding schools which he described as "private lunatic asylums", he always spoke up for abused children in his stories, while angrily condemning adult cruelty and neglect. His account in his autobiography Boy of the sheer pain of being beaten has never been bettered. He also writes beautifully about the joys of reading, and would have been horrified at today's spread of screen entertainment. Best of all, he combined in his fiction grotesquerie and black humour – an inheritance from the stories told to him by his Norwegian mother – with the more optimistic, get-up-and-go spirit found in British fairy tales. The end result was a succession of unsqueamish stories alternating between darkness and light before coming to thoroughly upbeat endings.

Dahl's own story is ably told by Donald Sturrock in this current biography, drawing on previously unavailable records of his work in wartime America for British Intelligence. Other episodes from his life, such as his plane crash in Egypt in 1940, the early death of his beloved daughter Olivia, and the near-fatal stroke of his first wife, the film actress Patricia Neal (pictured with Dahl, below), all receive full and sensitive treatment. A pity, then, that there is so little in these 655 pages about the books themselves.

There is still a case to be heard against Dahl, but here Sturrock generally prefers to look the other way. Dahl once declared to his future wife that "I would rather be dead than fat", and certainly there is no pity in his books for the overweight or ugly. (His editor at Puffin, Kaye Webb, wept at the prospect of publishing Matilda, with its cruel caricatures of two uneducated and generally revolting working-class parents.) His lifelong connection with his inner child, so useful when it came to writing for the young, had its downside when it also enabled him to replicate playground humour of the less appealing kind.

But ultimately, Dahl comes over as far more hero than villain. Who could be angry for long with someone who, when young, enlivened a stuffy embassy drinks party by entering with a red chamber pot on his head, and who later christened the pompous Oxford historian Sir Isaiah Berlin, his co-worker in British Intelligence, "the White Slug"?

In constant pain following his wartime accident, Dahl still managed to be a highly involved father to five children, a greyhound trainer, an antiques expert, an inventor, an excellent cook and a generous benefactor. And then there are the books. Fizzing with life, they are impossible to read without smiling. Try the opening chapter of The Witches, and see for yourself.