Deep within the vaults of a building, just off a busy roundabout in Maidstone, sit a collection of letters which, combined, would likely fetch close to £1 million were they to ever go under the auctioneer’s hammer.

They are stored in a fire-proof safe within the strongrooms of the Kent History and Library Centre – better known to many simply as the Kent Archives building, a modern, eye-catching site close to Maidstone United’s Gallagher Stadium.

Few have ever seen them – fewer still have ever been allowed to touch them.

Because they are penned by one of the most celebrated authors of all time – Jane Austen.

It is thought just 160 of the thousands she penned to family and friends during her short life – she died more than 200 years ago at the age of just 41 – still exist in the world today. Some are held by deep-pocketed collectors (one letter to her sister sold at London auction house Sotheby’s in 2017 secured £162,500) while others are kept by some of the world’s foremost libraries and institutions.

Yet the collection in Maidstone is one which is close to priceless for Austen’s legion of fans who continue to celebrate the woman who brought us classics such as Pride and Prejudice, Sense and Sensibility and Emma.

The letters were written by Austen to her niece, Fanny Knight. They date between 1814-1817. One was written just months before the author’s premature death and discusses her illness (she is thought to have died from either cancer or Addison’s Disease – a rare disorder of the adrenal glands).

Fanny Knight – daughter of Jane’s brother Edward – was born and grew up in Godmersham, near Ashford. Her stately home is believed to have been a key inspiration for the literary endeavours of her aunt. It is also just one of numerous, significant links she had with the county.

The letters – which frequently discussed Fanny’s love life – were published by Lord Brabourne in 1884. It would be one of his ancestors who would donate them to the Kent library.

After Jane’s death, Fanny had married Sir Edward Knatchbull (whose son would become the first Baron of Brabourne) – whose family home was in Mersham-Le-Hatch, near Ashford.

Thus, the letters from the author were kept in the Brabourne family. Fanny – whose diaries are also stored in Maidstone – is laid to rest, alongside her husband, in Lynsted.

Explains a spokesperson for the Kent Archives: “These letters were published with the remainder of the Jane Austen letters by Lord Brabourne in 1884, but were not sold – as were the remainder – a few years later.

“The letters are part of the Knatchbull family manuscripts.”

The documents were donated to the archives in 1962 by the then Lord Brabourne – John Knatchbull. The celebrated film producer and his family were on the boat blown up by the IRA in 1979 which killed Lord Mountbatten. Lord Brabourne and his wife, Patricia Brabourne, were both injured in the blast, while his mother and one of their twin sons were also killed in an explosion which made headlines around the world.

Margaret Wilson, from Tonbridge, is a member of the Jane Austen Society and has penned books on Kent’s links to the author.

“I was allowed to see the letters many years ago,” she recalls.

“But they don't let people touch them and they’re not on display – they’re much too valuable.”

Adds a spokesperson for the Kent Archives: “The secure strongrooms are environmentally controlled so that the archives are kept at the optimal temperature, humidity and with as little exposure to light as possible.”

Mrs Wilson was, like so many before her, bitten by the Austen bug as a youngster.

Now in her 80s, she explains: “I remember I won a prize at school and we were able to choose what book we wanted. I chose one of her novels. I was about 13.

“She's so good at understanding how human nature works. Her novels are very deep – they may not appear to be so – but she really does understand people and although she never married she understands a lot about relationships.

“She came from a very large family and she knew a lot of people during her life. A lot of that is reflected in her novels. She writes about the human condition and all the problems that people have and most of the people who read her enjoy the way she does it.”

That large family were originally based in Horsmonden – with Jane Austen’s father attending Tonbridge School (where he would return as a teacher in later years) before Oxford University, eventually living in Hampshire as a rector. It was there, in 1775, Jane was born – one of eight children.

Her brother, Francis, lived and worked at a law firm in Sevenoaks.

But it was her brother, Edward, who would prove such a draw – and his lifestyle an inspiration – to the young author.

His life certainly took an twist at the age of 12 when he was adopted by a wealthy childless couple. They were relatives of his father and it was far from unusual for such an arrangement in order to allow him to become their heir.

As a consequence, he would ultimately take over the couple’s wealth and with it a number of properties in both Hampshire and Kent.

Edward moved to and lived in Godmersham Park, a sprawling estate between Ashford and Canterbury. As a stipulation of the inheritance, he changed his name to Knight.

But his relationship with sister Jane was undimmed.

Explains Margaret Wilson: “She was very close to Edward. He was a very affable person by all accounts – a very easy person to like.”

While in Kent, she would also stay at Goodnestone Park, near Canterbury, where the family of Edward’s wife lived, as well as nearby Rowling.

Did she use the grand settings and social circles to which she was exposed to influence her writing? It seems likely.

Adds Mrs Wilson: “I’m sure Kent influenced her. When she stayed with Edward, it was in a really big house whereas her own family situation was a vicarage in Hampshire.

“Edward had servants so it was like living a different kind of life. She must have been affected by it. She used to write in her letters to her sister [Cassandra] saying how comfortable she was there.”

As is well documented, Jane Austen's books met with only modest success while she was alive – her name was not on any of her books published during her lifetime; a situation not uncommon for women writers at the time.

She died, in Hampshire, in 1817 at the age of 41.

In one of the letters held in Maidstone, she writes to her niece: “'I must not depend upon being ever very blooming again. Sickness is a dangerous Indulgence at my time of life."

The letter was dated March 1817. She died four months later.

It was only in the mid-19th century her books began to reach a wider audience. Today they are best-sellers around the world. Pride and Prejudice is estimated to have shifted 20 million copies alone as well as spawning a host of small and big screen adaptations – keeping her relevant to a modern audience.

Today, the Jane Austen Society has members and branches around the world – from the US to Australia, Japan to Pakistan.

In Kent, there are walking trails and plaques to recognise the people and areas from which she drew inspiration.

Those carefully guarded letters, kept under lock and key in the county, are valuable proof of our collective link to a literary great.