Mr Pickwick, Samuel Weller, Nicholas Nickleby, Smike, Mr Micawber, Little Nell, Quilp, Sarah Gamp, David Copperfield - vivid, fully-fleshed characters, grotesque, endearing, comic, all too human and invariably larger-than-life - issue forth from the pages of Charles Dickens with all the energy of a swarming army determined to march forever, writes Eileen Battersby

No author, either before him or since, with the possible exception of Shakespeare, assembled such an unforgettable host. Among Dickens's fellow 19th-century storytellers, there are of course, other masters, such as Dostoyevsky, Balzac, Tolstoy and Zola, each of whom created tenacious immortals who also live off the page.

Dickens, however, is an irascible original; a storyteller and social commentator. He invented complex, layered plots incorporating outrageous coincidences with a frenetic genius. Moreover, he published according to the serialisation format of his times, and for a market that expected illustrations.

It took talented artists to meet the publishing demands: deadlines were short, competition was tough - artists often approached writers - and an illustrator might find himself having to sketch a story that was not yet finished, or perhaps not even written. Dickens knew exactly what his creations should look like and ensured his illustrator's images were worthy of the task.

Several illustrators were to work with him throughout a career that produced millions of words and hundreds of vivid set pieces. George Cruikshank is revered for his Dickens images, yet illustrated only Oliver Twist, albeit memorably.

Another artist illustrated 10 Dickens novels: Posthumous Papers of the Pickwick Club (1837), Nicholas Nickleby (1839), The Old Curiosity Shop and Barnaby Rudge (both 1841), Martin Chuzzlewit (1844), Dombey and Son (1848), David Copperfield (1850), Bleak House (1853), Little Dorrit (1857) and A Tale of Two Cities (1859) in the course of a 23-year collaboration that began in friendship and ended in acrimony. His name was Phiz - Hablot Knight Browne.

While his illustrations are immediately familiar to readers of Dickens, the details of his life are not. His story is told in a new biography, Phiz: The Man Who Drew Dickens by Valerie Browne Lester, his great-great-granddaughter. It is a lively, detailed account that is, hardly surprisingly, dominated by the giant personality of Dickens himself.

When Phiz first began working with Dickens, he was just 20, while the future great writer was only 24. Already a dashing young man about town, eager to dispel the horrors of his grim childhood, Dickens had proven himself to be a talented journalist and sketch writer.

He had been approached by Robert Seymour, a well-known, popular artist and acknowledged heir to the great master of the grotesque, William Hogarth, in search of an author to "write up" a series of his pictures. As far as Seymour was concerned, any young writer should feel privileged to work for him.

Dickens, who was 14 years younger, felt otherwise, and so imposed his personality on Seymour's pictures so that they quickly became secondary to the text Dickens was creating. Suddenly The Pickwick Papers was born. Seymour was bewildered. On the morning of April 19th, 1836, he wrote a note to his wife. "Best and dearest of wives . . . blame, I charge you, not any one, it is my own weakness and infirmity". Then, as Lester writes: "He took up his fowling piece, went out into his garden, and blew out his brains."

Admittedly, Seymour was of a melancholy temperament. Phiz was different. Affable, easy-going and slow to rise each morning, in him the domineering Dickens found the ideal collaborator, an enthusiastic 20-year-old with a sufficiently placid personality to survive the mood swings of a driven writer who never declined a commission.

There is no doubt that with Lester's story of Phiz, as with any story that involves Charles Dickens, the Victorian master takes over. The author recalls being advised while working on the biography, "to keep Dickens at bay". But this proved difficult for her and also proves difficult for the reader.

Phiz has a story in his own right. Introduced to the world as the 14th child of an old Huguenot London family, he was in fact the son of the Browne family's eldest daughter, Kate, who had become engaged during the family's stay in France to a Capt Hablot, a member of Napoleon's Imperial Guard. He disappeared during the Battle of Waterloo, presumed killed in action.

Little Hablot was raised as the child of his grandparents. Although Capt Hablot did resurface briefly, Kate was not to see him again and never married. When her son, Hablot, was seven, his "official father", really his grandfather, William Loder Browne, abandoned his family, setting off for America at the age of 51. There he reinvented himself and lived happily for a further 33 years - dying, apparently in his sleep, aged 84.

So Hablot Knight Browne had the rather Wildean distinction of losing two fathers in rapid succession. These experiences may have encouraged him to be a good family man, as he in turn had 13 children and proved a kindly parent.

He also had a passion for horses, drew them brilliantly and rode throughout his life. He spent 12 years mid-career living in the country, which enabled him to have his own stables - although it distanced him from the commercial art world and reduced his commissions.

Lester writes with the love - and loyalty - of a proud descendant aware that Phiz, who was admired by Emily Dickinson, is not as famous as he should be. Yet, while Lester's diligently researched book is devoted to putting this right, she also evokes the colourful Victorian world in which he lived.

Phiz and Dickens enjoyed a working relationship that was for a long time a friendship that included many outings, such as trip to Yorkshire when Dickens was researching Nicholas Nickleby, but Phiz also worked with other writers including Trollope, Sheridan Le Fanu, William Carleton and Charles Lever.

In the course of retrieving her famous great-great-grandfather, Lester alerts readers to the neglected Lever. Born a child of privilege in Dublin in 1806, he was the son of an English architect father and an Irish Protestant mother.

Having studied medicine at Trinity College, Lever sailed to North America, notched up a number of adventures and returned to Ireland via Germany, where he finally completed his medical studies.

He battled a cholera outbreak in Co Clare before moving with his new wife to Portstewart, Co Derry. There he began writing his rollicking tales of Irish rural life. The Confessions of Harry Lorrequer (1840) was the first of many which included Charles O'Malley the Irish Dragoon (1841), Jack Hinton (1843) and Tom Burke of 'Ours' in the same year. Lever recruited Phiz to work with him and he illustrated 16 of the Irish writer's novels and the pair enjoyed easier relations than Phiz did with Dickens.

Their partnership spanned 26 years and Lever's various moves. He never demanded previews of Phiz's work, but was late with copy. Lever also managed to anger Irish nationalist opinion with his humour which was dismissed by Carleton as, according to Lester, "caricaturing and debasing of Irish life". As for Dickens, Phiz's work on Dombey and Son marked a major development in the artist's ability to portray the darker aspects of Dickens's work. But by Bleak House, Dickens had begun to distance himself from his illustrator and criticise his work.

Little Dorrit saw their relationship in crisis. It staggered on until the publication of A Tale of Two Cities in 1859. Perhaps the real problem was that Dickens, the most visual of writers, simply outgrew the need for illustration. He died suddenly in 1870.

Phiz lived until 1882, refusing to comment on his former collaborator's abrupt passing. Ironically, both had long destroyed their respective correspondence with each other.

A further, lasting irony, particularly pertinent at this time of year, is that A Christmas Carol (1843), that most enduring of seasonal polemics, was illustrated by John Leech - much to the resentment of Phiz, whom Dickens may have considered too busily occupied at the time with the closing chapters of Martin Chuzzlewit.

Phiz: The Man Who Drew Dickens by Valerie Browne Lester is published by Chatto & Windus, price £20