THE POET Louis MacNeice called her “incorrigibly plural”: Helen Cresswell brought the phrase into the title of an essay about her own writing as best summing up what she saw as the infinite possibilities of storytelling.

When young she was a voracious reader, conscious that she would eventually become an author, and there is indeed an incorrigible plurality in the many books, plays and adaptations that make up her life’s work.

Cresswell was born in Nottingham in 1934, into a family whose eccentricities were reflected with much exaggeration in the antics of her characters, the Bagthorpes. After Nottingham High School for Girls she went on to read English at King’s College London (although she claimed that she had already read well beyond the syllabus and thus spent much time in undergraduate argumentations).

After graduating she worked in various jobs, including teaching, but with the acceptance of the manuscript of her first book, Sonya-by-the-Shore (1960), Cresswell began a career that would place her among the most prolific and best-known writers for children of her generation.

Her next two books were Jumbo Spencer (1963), first of a four-book series about a sanitised William Brown, and the romantically conceived White Sea Horse (1964), and while these may be seen as ’prentice work they display elements that were to characterise many of the books — more than a hundred — that were to follow: a zest for portraying larky, independent children and a poetic treatment of fantastic events which are nonetheless rooted in the everyday world.

The two aspects were fused a year or two later in The Piemakers (1968), the now celebrated tale of how the Roller family of Danby Dale create a steak-and-kidney pie substantial enough to satisfy two thousand local pie-fanciers and thereby win a Royal Patent and, even better, a hundred-guinea prize. The story, which was the first of four to be commended by the judges of the Library Association’s Carnegie Medal, was singled out by Cresswell herself as the book whose writing gave her the most pleasure and the one in which she “found the right voice form to speak with”.

Once found, that voice applied itself to many purposes, transmitting itself from pen to paper on a rosewood desk said once to have been used at her publisher’s by Walter de la Mare and T. S. Eliot. With professional skill she worked on simple stories, such as Rug is a Bear (1968), for reading beginners, and an educational series for reluctant ones.

Among many short stories the most popular were those about the unappetisingly-named Lizzie Dripping, devised both for performance on television and for publication. The potential shown there for sequences of tales involving the same characters led to other series such as that for younger readers about Posy Bates (1990-94) and the long-running Bagthorpe Saga, which began in 1977 with Ordinary Jack and had nine sequels.

Cresswell once characterised her work as a sustained exploration of the powers of creative imagination set against the rationalism of technocracy. While the wildly unpredictable trials of the Bagthorpe family, Lizzie Dripping and the Piemakers have found Cresswell her widest audience, the succession of children’s novels that succeeded The Piemakers may remain her most original achievement.

These stories, which began with the rather pale Piemakers lookalike The Signposters (1968), were criticised because of Cresswell’s observed difficulty in shaping them towards satisfying conclusions. She abjured the procedure of writing to a preordained plan: “If I tried to work out a fantasy in advance, with all the symbolism neatly tied up”, she said, “it would be stone dead before I started”.

Her methods served her well: The Nightwatchmen (1969), The Beachcombers (1972) and The Bongleweed (1974), which all contained elements of mystery, were among her most admired books; and The Winter of the Birds (1975), her most ambitious and powerful novel, on which she lavished great attention, was a success despite its bleakness and perplexing concepts.

Cresswell’s comradely addresses — “If you had been a seagull you would have seen” — “Before you begin, imagine yourself down on an East Coast beach” — drew her readers in. Her descriptive powers, especially of landscape, and her handling of dialogue, were extraordinary.

This last qualified her for the much neglected craft of scripting narratives, primarily for television production. As with Lizzie Dripping, certain of her works were set in specific locations: The Secret World of Polly Flint (1982) at Rufford Country Park, Moondial (1987) at Belton House, were conceived for television, although story and script were written almost simultaneously; and she also worked on adaptations of stories by other writers for children such as E. Nesbit and, perhaps surprisingly, Enid Blyton.

Cresswell had married Brian Rowe, a childhood friend, in 1962. They were divorced in 1995. They had made their home at a Georgian farmhouse set in the Nottingham countryside where she devoted much time to developing the gardens — good inspiration for The Bongleweed.

In recent years she suffered increasingly from the cancer from which she died. She is survived by her two daughters and two grandchildren.

Helen Cresswell, children’s author and scriptwriter, was born on July 11, 1934. She died on September 26, 2005, aged 71.