A Charlotte Brontë manuscript is heading to France after being sold for £690,850 at Sotheby's in London. The miniature booklet, one of six handwritten "Young Men's Magazines" made by the author when she was 14, was bought by La Musée des Lettres et Manuscrits in Paris for more than twice the pre-sale estimate.

The manuscript is set in Glass Town, a fictional world created by the teenage Brontës, and contains 4,000 words over 19 pages small enough to fit in the palm of a hand. Formerly in a private collection and previously untraced, it contains ideas later fleshed out in Brontë's novels.

One scene, says Sotheby's book specialist Gabriel Heaton, anticipates one of the most famous episodes in Jane Eyre, in which Bertha, Mr Rochester's mad wife, tries to kill him by setting fire to the curtains in his bedroom.

The French museum outbid by £20,000 the Brontë Parsonage Museum, owned and run by the Brontë society at the writers' former home in Haworth, West Yorkshire. "It's particularly disappointing that this manuscript was in a series," said its director, Andrew McCarthy. "We have four of them at Howarth and the other is untraced. It's a shame that it's not coming back to join the other four."

Lucasta Miller, author of The Brontë Myth, described the sale as "a genuine loss. This manuscript embodies a phase in [Charlotte Brontë's] early development, and provides real insights into how she went on to produce her mature masterpieces, Jane Eyre and Villette. As a physical object it is not just of sentimental value. The tiny pages and the microscopic writing embody the nature of her creativity so uncannily that you have to see the manuscript in the flesh truly to feel and understand how her imagination worked."

La Musée des Lettres et Manuscrits intends to put the manuscript on display in January. Sarah Laycock, Library and Collections Officer of the Brontë Parsonage Museum, said they would request a transcript so that Brontë scholars would be able to make use of the pamphlet, while McCarthy said he hoped they could arrange a loan.

This year saw film adaptations of both Jane Eyre and Emily Brontë's only novel Wuthering Heights released within weeks of each other. The boom in interest in the Brontës has proved a double-edged sword for specialists.

"The films have generated a lot of interest," said Laycock. "This auction's had a lot of media attention and that may have driven up the price."