A book smaller than a playing card and containing 10 unpublished poems, is returning home to the West Yorkshire parsonage where it was written in 1829 by the 13-year-old Charlotte Brontë.

The book, thought to be lost, has been bought in New York for $1.25m (£1m) with Haworth in mind. It measures just 10cm by 6cm, and it is probably, centimetre for centimetre, the most valuable literary manuscript ever sold.

“It is phenomenal really,” said Ann Dinsdale, principal curator of the Brontë Parsonage Museum. “I haven’t been able to take it all in yet.”

The manuscript is one of the “little books” written when Charlotte and her siblings Emily, Anne and Branwell were children. It is titled ‘A Book of Ryhmes [sic] by Charlotte Brontë, Sold by Nobody and Printed by Herself'.

Dinsdale said: “She’s known for her novels but initially Charlotte wanted to be a poet. We know that she sent samples of her poetry to the poet laureate.” The poet laureate was Robert Southey who advised her against a literary career. “Literature cannot be the business of a woman’s life: and it ought not to be,” he wrote.

The titles of the poems have been known to experts. They include On Seeing the Ruins of the Tower of Babel, Songs of an Exile and Meditations While Journeying in a Canadian Forest. The poems themselves have never been published, photographed, transcribed or even summarised.

A Book of Ryhmes is the last of more than two dozen miniature books created by Charlotte to remain in private hands. It was last seen at auction in New York in 1916 where it was sold for $520. It then disappeared with its whereabouts, or survival, unknown until now.

When it emerged that the book would be a star of last weekend’s New York International Antiquarian book fair, the UK’s leading literary heritage charity sprang into action. The Friends of the National Libraries (FNL) was founded in 1931 to help save the UK’s written and printed history. Geordie Greig, chair of FNL, said they had only two weeks to raise the money to buy the book. “Saving Charlotte Brontë’s little book is a giant gain for Britain,” he said. “To return this literary treasure to the Brontë Parsonage where it was written is important for scholars and also students studying one of our greatest women writers.”

The manuscript is being donated to the Brontë Society whose museum in Haworth has the largest collection of Brontë manuscripts in the world. Dinsdale said it was likely all four Brontës made little books or magazines when they were children, although none survive by Anne or Emily. The four siblings created a sophisticated imaginary world with a nation called Angria and a city called Glass Town, filled with their childhood heroes.