Is this the real Mr Toad?

Generations of children and adults have been enchanted by the exploits of Ratty, Mole and Badger in Kenneth Grahame's The Wind in the Willows, yet it is the adventures of the book's over-zealous anti-hero, Toad of Toad Hall, that have proved the most enduringly popular.

Now, archived correspondence released from the Bank of England, where Grahame worked for 30 years, is set to shed new light on the author of the children's classic – and suggest a real-life model for the overbearing Mr Toad, whose disastrous motoring outing, prison escape and battle to evict squatting stoats have been the subject of numerous stage and television adaptations.

Grahame joined the Bank of England as a young man and rose to the position of Secretary by the age of 39, becoming the youngest person to hold this senior role. Yet he resigned in unexplained circumstances in 1908, shortly before the publication of The Wind in the Willows, which was originally written in letter form in 1905 for his son, Alastair, who committed suicide in 1920. Until now it has always been thought that a bizarre incident in which a deranged man entered the bank and fired three pistol shots at Grahame in 1903 – each missing – led to a nervous condition resulting in his resignation. Now the bank has released several personal letters from and about Grahame which suggest the problem was in fact a breach with one of his superiors – who became the model for Toad.

The documents, which will form a permanent exhibition to mark the 100th anniversary of the publication of the book in October, include Grahame's resignation letter, dated June 1908, in which he blames his mental health for his decision to leave the bank. "For some time past I have been forced to realise that the constant strain entailed upon me by a post of so much responsibility is telling on me in a way that makes me very anxious, both as to my ability to continue rendering a proper and efficient service and as to the wisdom of facing further deterioration of brain and nerve," he writes.

However, other correspondence from the archives shows the bank's doctors disagreed that Grahame was under mental strain, and the calculation of his pension showed he was paid half of what he might have expected for 30 years' loyal service, suggesting he left under a cloud.

A letter from 1950, written by a contemporary of Grahame's at the bank in response to a query by the then archivist and never published before, shows that Grahame had a major falling out with one of the bank's directors, Walter Cunliffe, who went on to become Governor of the Bank of England. "His retirement had nothing to do with ill health, but to a resentment of the bullying manner of a director with whom he was discussing some official business, when he was provoked into saying 'You, sir, are no gentleman'," writes the man, Marston Acres. "I believe the director concerned in this episode was Walter Cunliffe (afterwards Lord Cunliffe), whose overbearing manner made him the terror of the high officials in later years when he was governor." Mr Acres goes on to explain that Grahame was not seen at the bank after the incident, and was asked to resign.

The bank's current archivist, John Keyworth, explained that the documents have never before been made public because of their personal nature. "It is now 100 years ago and is part of history," he added. "Walter Cunliffe was renowned as being a very autocratic man – he even had a row with the Prime Minister Lloyd George. There is nothing to back it up, but if Toad was based on anybody [Grahame] knew, Cunliffe would be the obvious one."

Cunliffe's grandson, the third Baron Cunliffe, said he was intrigued. "I remember visiting my grandmother as a boy and there was an ancient Renault in the barn, which was my grandfather's. He was an early adopter of the motor car, so yes, he would have driven around going Poop! Poop!"