Revealed: why Brocklehurst's inspiration threatened to sue Brontë

Charlotte Brontë did not opt for subtlety when she decided to get her own back on the teachers who had made her life a misery.

Drawing graphically on her torrid days at the Clergy Daughters' School at Cowan Bridge, Lancashire, she recreated it as the legendary Lowood School, in her novel Jane Eyre. This was a place where the physical abuse young Jane endured "without a reason" led her to conclude that "we should strike back again very hard; I am sure we should - so hard as to teach the person who struck us never to do it again."

This and other comments, including Jane's conclusion that "the lessons appeared to me both long and difficult: the frequent change from task to task, too, bewildered me," have given the Clergy Daughters' School an important place on northern England's Brontë heritage trail.

But now letters have come to light which reveal that, despite the novel's acclaim, Brontë's furious headmaster did not take the attack lightly and threatened to sue his most famous former pupil.

The school's founder and head, the Rev William Carus-Wilson, was the inspiration for Mr Brocklehurst, Lowood's autocratic head. The fearsome Brocklehurst was "little liked here; he never took steps to make himself liked". His real-life counterpart was no different. Having taken great exception to the portrayal of himself and his school in Jane Eyre when it was published in 1847 he took legal advice. Court action was only avoided after Brontë wrote an apology, pointing out that she had used literary licence to exaggerate the details.

The row has emerged in three letters by Carus-Wilson's grandson, Edward Carus-Wilson, which were written in 1912 when Carus-Wilson sold a revised manuscript by Brontë for 10 guineas (£10.50) to an autograph collector to raise cash to pay for his child's medical treatment.

"She did not write favourably of the school and my grandfather was advised to take it up publicly, if not legally, but he refrained from doing so," Carus-Wilson writes in one of the letters. "He ... wrote to Charlotte Brontë to remonstrate with her and the result was that she wrote the sketch that I have in my possession, retracting a good deal of what she had formerly written about the school in Jane Eyre.

"Charlotte Brontë sent it to my grandfather as a kind of apology for what she had written against the Clergy Daughters' school in Jane Eyre and gave him permission to publish it and state, if he wished, that she was the writer of it. My grandfather never published this, but kept it by him and as I told you in my last letter, it passed to my father in 1883 and then to myself."

The school remained a controversial subject when Brontë's biographer, the Victorian writer Elizabeth Gaskell, began tackling it. Mrs Gaskell had to re-write one offending passage in her biography, toning down accusations that Cowan Bridge's harsh regime and inadequate food was responsible for the premature deaths of the elder Brontë sisters, Maria and Elizabeth, and for the ruin of Charlotte's own health.

Now the hunt is on for Brontë's revised manuscript. "It really is the most tantalising mystery" said Richard Westwood-Brookes, a documents expert at auctioneers Mullock Madeley, who expects the letters to sell for up to £100 at auction in Ludlow, Shropshire, next month.

"We don't know who the collector [of Carus-Wilson's letters] was. I would imagine the collector kept the letters as provenance of the genuineness of the manuscript, but at some stage it went to someone else who didn't want the letters.

"This folder has probably passed from one dealer to another and changed hands many times. I doubt whether whoever sent it to me has read the letters and nobody has made the connection."

Alan Bentley, the Brontë Parsonage Museum's director, said that since Jane Eyre was originally published under a pseudonym, it was difficult to ascertain whether Carus-Wilson knew whether Charlotte Brontë, his former pupil, was the author.