The Graham family, who have owned Norton Conyers since 1624, had suspected that a staircase to the attics was concealed somewhere inside the sprawling stately home, which has medieval origins and later additions.
The reason? Author Charlotte Bronte had visited in the 19th century, and based her most famous work, Jane Eyre, on both a legend of Norton Conyers and the house itself.
In 1839 Charlotte learned of the story of a mad woman who was confined to an attic bedroom - this grisly myth inspired the character of Mrs Rochester, and the house became the fictional Thornfield Hall.
The novel included passages describing a staircase that current owner Sir James Graham felt sure was based on one that Charlotte had seen at Norton Conyers.
He had heard older relatives talking about the hidden steps, and the Grahams eventually sought approval from English Heritage to lift floorboards in an attic room once used by servants to reveal the top of the staircase. The exit door was found behind a dresser on the main landing.
However, the staircase was in poor condition and access had to be limited for safety reasons.
Sir James and his wife Lady Halina inherited his family seat in 1982, and began a 20-year restoration programme that resulted in Norton Conyers being removed from Heritage England's Buildings At Risk register and opened to the public for the first time in a century.
It's full of fascinating features, including a huge hall with a table dating from the Middle Ages, and King James's Room, where the future King James II stayed overnight in 1679.
But all did not run smoothly for the hall as a visitor attraction - it was later forced to close for another eight years after the discovery of a devastating infestation of death watch beetle. It re-opened in 2015 with a newly-installed central heating system.
The couple are amusingly candid about the eccentric moments of life in a country house, recounting stories of foxes dashing through open doors while being pursued by the local hunt.
“People see all the acres in front of the house but don’t see the reality of it which is that it is such hard work and it is never ending, and there’s always something going wrong,” explained Lady Halina.
Sir James added: “Landed we are - but rich we are not.”
They now open for around 30 days each year, and private tours can be arranged. There's also a stunning 18th-century walled garden with orangery, pond, herbaceous borders, parkland and plant stall.