Charles Dickens, By Michael Slater

Dickens's ruthless ambition grew from family failure. His father constantly ran into trouble with money, and was eventually imprisoned for debt. In what has become one of the most familiar episodes in any writer's life, 12-year-old Charles was sent to work in a dingy blacking factory, sitting in a window to paste labels. Idlers would gather to watch. The shame was overwhelming, but it could not crush Dickens's relish for what London offered, even to a "common labouring boy".

He listened to stories about the deranged "White Woman of Berners Street", habitually dressed as a bride; decades later, he remembered her in Miss Havisham. He saw coal-heavers dancing, went "with a very motley assemblage" into a show-van to inspect the Fat Pig, the Wild Indian, and the Little Lady, swaggered into a pub to order a glass of "the very BEST" ale.

The result was an unusual awareness of himself and others, exposed in performance or display. Young Charles was not planning to restore his fortunes through fiction, but his miseries made him a novelist. Critics have said as much before, and Michael Slater's distinguished study, the product of a lifetime's research, presents no dramatic discoveries. What makes this biography fresh is its sensitivity to the dualities that drove Dickens's writing.

A collision of painful uncertainty and unshakable self-belief fuelled his energies. The confidence is more remarkable than the anxiety. Where did it come from? Partly from his father, who (like Mr Micawber) never allowed catastrophe to dampen his spirits for long. Dickens came to condemn his mother for carelessness, but it freed him from the weight of expectation.

For emotional sanctuary, he turned to his sister Fanny, who foreshadowed the tender brother-sister relations that haunt his fiction. She died of tuberculosis, and Dickens was deeply moved by her final illness: "in the night, the smell of the fallen leaves in the woods where we had habitually walked as very young children had come upon her with such force that she had moved her weak head to look for strewn leaves on the floor by her bedside."

Dickens catches his readers' imagination with sharply sensuous details like these, always infused with feeling (pathos, indignation, amusement). He has no interest in abstract generalisation. We are held by the scene before us, looking for the "strewn leaves" that we know to be an illusion. Immersed in the writing of Barnaby Rudge, Dickens thought about what he was doing with a sort of wonder. "I sit down to my book, some beneficent power shows it all to me, and tempts me to be interested, and I don't invent it – really do not – but see it, and write it down."

What Dickens describes is a theatrical experience. Slater's book shows that drama and fiction were hardly separate in Dickens's mind. He was gripped by the popular plays and pantomimes he saw in his youth, and first attempted to write for the stage at the age of ten (Misnar, the Sultan of India; a long, oriental tragedy).

His inclination to earn his living as an actor came before his earliest attempts at fiction. The nervous strain imposed by his later passion for performing his work in public damaged his health, but it was the culmination of a rooted compulsion in his work.

Speeches, readings and amateur theatricals gave him the contact with an audience he craved. These activities mattered intensely to him, and the serial publication of his fiction created a comparably sustaining relation with readers. His tireless work as a journalist and editor, another dimension that Slater considers with expert care, added to his fame.

Phenomenally high sales figures were, for Dickens, more than a matter of commercial success. He felt a personal bond with his readers, and often spoke of the "affection and confidence" between them. He came to need their adulation, but had a keen sense of the responsibility that went with it. "A writer with a great audience... has his duty to do, and he must do it."

It was an obligation that involved vigorous campaigns for education, or the humane treatment of the sick and destitute, or the rehabilitation of women who had fallen into prostitution. Dickens's self-respect rested on his growing prosperity and reputation, and the status (another matter for campaigning) of professional writers. But it also involved working for the dispossessed, whose wretched fate he had himself barely escaped.

A blameless private life was essential to his public dignity. Dickens had married early, and his amiable but unremarkable wife Catherine had borne him ten children. His loyalty wore thin as the years passed, and the marriage was wrecked when in 1857 Dickens met Nelly Ternan, an 18-year-old actress. He was 45, and at this point the doubleness that had formed his life became a matter of real distress, for himself and his family.

Catherine was forlornly banished, and Nelly, whose feelings for Dickens remain obscure, was hidden away, to be supported and regularly visited by her lover. Slater, who is generally on Dickens's side, is evidently uncomfortable about this affair.

Dickens was vociferous in self-justification, but his behaviour was shabby. However, duplicity continued to enrich his fiction. His novels darken, peopled by men with hidden lives and double identities (Sidney Carton, John Rokesmith), or racked by frustrated love (Bradley Headstone, Pip). His women (Estella, Bella Wilfer) acquire more force and complexity than his younger, simpler notions of female virtue. The youthful exuberance never quite disappears, but is brought up short by the limits of its assurance.

These tensions only accelerated Dickens's astonishing productivity. "As to repose – for some men there's no such thing in this life," he remarked. Slater does justice to the dedication that Dickens brought to the business of authorship. Family responsibilities, a hectic social calendar, polemical crusades, the day-to-day demands of managing his journals, secret encounters with Nelly; nothing was allowed to get in the way of "that invincible determination to work, and that profound conviction that nothing of worth is done without work".

He died in 1870 with his last novel, The Mystery of Edwin Drood, unfinished. His fiction is still producing a stream of vivid adaptations, as new generations of admirers find their own reasons for devotion. Dickens's life might feel like a fairytale, transforming poverty and neglect into dazzling triumph. Readers of every description will find something bleaker in Slater's authoritative account, for as Dickens knew "the life of almost any man possessing great gifts would be a sad book to himself". But the story remains irresistible.

Dinah Birch, professor of English at Liverpool University, has edited the new 'Oxford Companion to English Literature'