A couple who spent 15 years renovating their dream farmhouse, only to see it destroyed in a blaze, vowed yesterday to start work all over again.

Peter Coverdale, 49, and his wife, Sue, 47, had spent thousands of pounds restoring Levy Pool, a Grade II-listed property in Bowes, near Barnard Castle.

It has been described as a "historical gem".

Mrs Coverdale was putting the finishing touches to a bedroom, and her husband was working outside, when the fire started at the weekend in the thatched roof, the only one of its kind in County Durham.

Mr Coverdale, who owns a masonry contracting company, said yesterday that the house had no roof or floors and part of the walls were missing when they bought it for about £60,000 in 1990.

At first, they lived in three mobile homes on the site with their three children - sons Nick, 29, Karl, 25, and daughter Stevie, 26.

As well as restoring the house, and having the thatched roof put on by a specialist from York, they renovated a barn to make an office and restored a cottage which is now Stevie's home.

All five stayed in the cottage on Sunday night.

Mr Coverdale said: "We put all our time and a great deal of money into making this our dream home, and we had it just about finished. I just can't understand how the fire started.

"We were careful to ensure no electric wires were near the thatch and the chimney was fully lined. The property was insured for £350,000, so the insurance people may do tests to find out how it started.

"We now have to start the work all over again. It is heartbreaking, but after putting all our efforts into it, we can't give up now."

The house was built in the 1600s and the family did all they could to put it back to its original condition after being told the roof was unique in the area.

Mr Coverdale's company has worked on several historic buildings in the area, including the Market Cross, in Barnard Castle.

Nick and Stevie both work for the firm and Karl is a trainee lawyer.

The family hope the insurance will pay for somewhere to live until the house is habitable again.

Firefighters battled the blaze for more than 12 hours.