A property developer told last night how he was lucky to be alive after a 200-year-old building he was renovating collapsed.

Graham Levy, 44, was removing timber beams from two terraced shops in Haughton Green, Darlington, when a chimney breast gave way.

The entire internal wall dividing the two properties crumbled to the floor and Mr Levy was left with injuries to his arm and leg.

"I'm lucky," he said. "I'm quite a tough cookie but this was a shock. Unfortunately it is the price you pay when you are trying to preserve an old building."

His partner, Barbara Dewing, said: "He was cutting the timber with a hand saw and the chimney breast just toppled on him.

All you could see was smoke and dust flying about. People from across the road saw it happen and came rushing across.

"I couldn't see him at first because I was outside. He is lucky to be alive but he is in a state of shock."

A neighbour said: "There was a tremendous bang. I looked out of the window and all the rafters were on the floor. All that was left was the front wall."

The couple, who live near Heighington, own about 35 properties and have 20 years experience in renovating old buildings. It is costing them £100,000 to convert the building, which has been used as shops for the last two decades, into two one-bedroomed cottages.

They have planning permission to alter and extend the property and had already removed the roof and back wall.

A structural engineer had told them the building was unsafe so they were using hand-held equipment to tackle the main span beams when the accident happened on Sunday afternoon.

Ms Dewing said: "For the safety of the adjoining buildings we had to do it like that. Unfortunately even the engineer didn't realise the wood beam above the fireplace was rotten, which was why it crumbled."

Mr Levy has made the property, which sits between a fish and chip shop and another cottage, safe but officers from Darlington Borough Council have told him to stop work.

"It's not as if I had gone along as a DIY person with a hammer and chisel," he said. "We are not Mickey Mouse people."

Ms Dewy added: "It's a major setback. Now it could end up just getting left for a year."

A council spokeswoman said: "The situation is under investigation by our planning department."