A PROJECT to tackle a deathwatch beetle infestation at the historic house which inspired Charlotte Bronte's Jane Eyre has unearthed 1,000 years of history at the site.

Sir James and Lady Graham said eight years' work to conserve their family's home of 11 generations, Norton Conyers, near Ripon, had revealed Viking pottery beneath the floorboards, a Tudor painted screen hiding a door behind 18th-century plaster and rare 18th-century wallpapers.

The couple said after experts revealed the property's timbers had been infested since it was built in the 17th-century and that some rooms could cave in within five years, they launched a £300,000 scheme which saw them having to live at bed and breakfast guesthouses for a year.

Sir James, whose family moved to the house in 1642, said he felt duty-bound to preserve the property, where they had found a secret staircase and room which inspired mad Mrs Rochester's room in Jane Eyre.

Before tackling the infestation, Sir James carried out a year-long census of the woodboring insects while Lady Graham cleaned every beam in the attic of the 40-room mansion, to see the extent of the problem.

When it came to removing floorboards to treat damaged joists in the vast Great Hall and peeling back plasterwork in other rooms, the couple, who had to live in the house with no heating or hot water, discovered a range of artefacts among tonnes of medieval rubbish.

Lady Graham said: "The Viking pottery proved there was a property of this sort at this site in the 10th Century. We had no idea it was so old.

"We had always wanted to know about the secret spaces in the house."

They spent £1,000 sending dull wallpaper dating to 1740-80 they found behind the head housemaid's cupboard to the US for it to be assessed and reproduced and were delighted to find it had once been a vibrant yellow and pink design.

Although the couple say they will never rid the property of the beetles and are currently restoring the King James Room, the Historic Houses Association and Sotheby’s have awarded them the 2014 Restoration Award.

Harry Dalmeny, chairman of Sotheby's, said: “The Grahams have achieved an heroic restoration. Their passion, extensive research and great attention to detail have lifted the veil on over 1,000 years of history, while retaining Norton Conyers’ impenetrable mystery.

"Almost 200 years after Charlotte Brontë, visitors will with no doubt be mesmerised by this fascinating house”.

The property will be reopened to visitors next July.