A number of 17th century "witchmarks" intended to keep evil spirits away from a member of royalty have been discovered at Knole House.

The marks were found under the floorboards and surrounding the fireplace of a room which was built for King James I, in anticipation of his planned visit to Sevenoaks.

They have been hidden for centuries and are believed to be linked to the Gunpowder plot of 1605, which was a failed assassination attempt against the King.

A few months before the marks were engraved, the infamous plot caused mass hysteria to sweep across the county. Accusations of demonic forces and witches at work were rife.

The etchings, also known as apotropaic marks, are described to be interlocking, chequered and v-shaped.

They were thought to form a 'demon trap', warding off demonic possessions and have been dated back to 1606 by archaeologists who used tree ring dating methods.

Experts from the National Trust believe the markings were carved by craftsmen working for the owner of Knole house, Thomas Sackville, in anticipation of a visit from the King - a visit he never made.

The discovery comes as part of the National Trust’s £7 million, five-year project, supported by Heritage Lottery Fund, to conserve Knole, one of Britain’s most important historic houses.

James Wright, an archaeologist at the Museum of London Archaeology (MOLA) said: “King James I had a keen interest in witchcraft and passed a witchcraft law, making it an offence punishable by death and even wrote a book on the topic entitled Daemonologie.

“These marks illustrate how fear governed the everyday lives of people living through the tumultuous years of the early 17th century.

“To have precisely dated these apotropaic marks so closely to the time of the Gunpowder Plot, with the anticipated visit from the King, makes this a rare if not unique discovery.

"Using archaeology to better understand the latent fears of the common man that were heightened by the Plot is extremely exciting and adds huge significance to our research about Knole and what was happening at that time.”

Nathalie Cohen, National Trust archaeologist, said: “It’s wonderful to be able to piece together the forgotten stories of those who lived and worked at Knole and to share them with our visitors.

"This is that once-in-a-lifetime chance to unravel the history of one of the largest houses in the country, from the rafters to the floorboards.”

This insight into the everyday folk beliefs of the past is just one chapter in the history of Knole’s 600 year past. It is part of investigative work that will continue throughout the house until 2018.

Although the showrooms are closed to the public for winter conservation work, Knole is hosting a series of behind the scenes tours led by project archaeologist Nathalie Cohen on November, 20 and 21 so that visitors can discover the witchmarks for themselves.

For more info visit www.nationaltrust.org.uk/knole or phone 0844 249 1895.