MAURICE OR THE FISHER’S COT. By Mary Shelley. With an introduction by Claire Tomalin. Viking pound;9.99.

The discovery of Mary Shelley’s lost children’s story in a boxroom in the north of Tuscany in Italy reads like a fairy tale in itself. Last November The Times reported that the little handwritten book, sewn with string, had been found in a wooden chest among archives of the Tighe family in Casa Cini, San Marcello Pistoiese - buried among school diplomas, train tickets, maps and photographs. And, in the best traditions of fairy tales and literary finds, it had surfaced in time for the 200th anniversary of the birth of the author of Frankenstein.

Scepticism is the watchword for such “discoveries”, and in this case the sceptics were asked to accept that the manuscript, missing since 1821, had eluded generations of international Shelley investigators.

But whatever our views on the background of Mary Shelley’s only story for children - traced in an introduction by Claire Tomalin - Maurice is interesting because of its reflection of the tragic histories of two families and of Mary Shelley’s bond with an 11-year-old girl who was passionate about books.

Shelley scholars also know the manuscript as the author’s “story for Laurette”. Laurette was the elder daughter of Margaret, Lady Mountcashell and George Tighe, Irish political exiles and members of the Shelleys’ circle in Italy. Lady Mountcashell, a former pupil of Mary’s mother, Mary Wollstonecraft, welcomed Mary and Percy Shelley when they arrived in Pisa after the death of their son William in Rome. Both women had lost children (three of Mary’s four children had died by the time she finished Maurice in 1820; Margaret had lost custody of her seven older children) and both, with their partners, were social outcasts because of their radical politics and unconventional households. Mary gave Laurette the manuscript of Maurice for her 11th birthday.

The sentimental tale of a kidnapped boy echoes the Romantic themes of Frankenstein, published two years earlier: childhood vulnerability, parental anxiety, loss and deep melancholy are all there, despite an ostensibly happy ending when Maurice is reunited with his parents after a sojourn in a fishing village (hence the subtitle).

Mary was depressed at the time of writing: her journal of August 1819 reads “to have won, and then cruelly lost, the associations of four years is not an accident to which the human mind can bend without much suffering”. Maurice provided an outlet for her feelings.

The tale was, Tomalin says, “put together by someone who knew how to delight a child”, especially a precocious child who loved to read. Although only 39 pages long, it is divided into three “books” like the adult novels of the day. Like Frankenstein, it employs a series of narrative voices.

Maurice would not thrill today’s young readers; even in the 1820s it was wrong for the market. Mary’s father, William Godwin, who published the moral tales that were then fashionable for children, rejected it in 1821, saying, “Your tale I think very pretty . . . but it would not make more than a shilling book.” It was not heard of again until 1976 when a Shelley scholar identified Maurice as the tale written for Lady Mountcashell and George Tighe’s love child, the great-great-grand-aunt of the present occupant of Casa Cini. But there was still no sign of the manuscript.

Mary later encouraged Laur-ette to write herself, but records her disappointment that, while the girl wrote intelligently about important issues, she expressed no original ideas. Laurette grew up to be a novelist and journalist, but was never published in England.

This beautifully produced book, with its original manuscript extracts and carefully researched photographs of Mary Shelley’s historical and geographical settings, will enchant devoted Shelley fans. And anything by the author of Frankenstein is bound to attract interest. Mary Shelley’s fame has now been eclipsed by that of Frankenstein’s omnipresent Creature, who appears on cornflake packets and TV advertisements for Coca-Cola.

But it is Claire Tomalin’s literary detective work, unveiling the intimate connections between the Shelleys and Laurette’s family, that is the truly exciting outcome of this discovery.