Two retired businessmen say they are being forced to spend thousands of pounds a year on a rotting mill in Bradford which is protected from demolition as it is in a conservation area.

Five years after Derek Wright and Rob Shearer moved their former Yorkshire Envelope Company out of Harris Court Mills in Great Horton Road, they have still not been able to sell the now derelict building because of the conservation order.

Potential buyers have walked away from it because of its state and now the third selling agents have taken the mill off its portfolio because they say it is too dangerous to show anyone round.

Thieves have stolen all the lead flashing from the roof, the elements have sent floors crashing to the ground and pigeons have taken over.

Mr Wright said five years ago they almost sold it for £1.5 million to a man who got permission to turn it into 137 apartments but he went bankrupt a week before the deal went through.

Since then other attempts to sell it have failed despite the asking price being dropped to just £250,000, said Mr Wright, who now lives in Knaresborough.

He has written to Prime Minister David Cameron asking for intervention to persuade Bradford Council to drop the conservation order but got a reply saying it was a local authority matter.

Mr Wright said: “No-one wants it with the conservation order. It would cost too much to put right. If it’s demolished they could build affordable homes on it. That’s what Bradford needs instead of building on green field sites.

“We no longer have to pay rates on it because there’s nothing left. All the pipes have been stolen – there’s no water, no electricity, no gas but we have to pay public liability insurance and the cost to keep it getting boarded up to try to keep vandals out.

“There’s nothing special about the place, it’s a basic box-build mill. There’s nothing of architectural value. We are both retired and can’t afford to keep paying for it any more. People don’t want old mills any more. We’ve tried writing to the conservation officers but they just sit there in their ivory towers, they won’t even come out to look at it.”

A Bradford Council planning spokesman said: “Harris Court Mills is part of a conservation area. This means that not just the building but the surrounding area is protected so it cannot just be removed.

“We would expect the owners to work with professional advisers to consider alternative uses for the buildings and look at how the most important structures on the site could be retained.

“Within conservation areas, planning policy aims to retain buildings which contribute to the character of the area. Demolition would be a last resort and only be considered if the merits of a replacement scheme outweighed the significance of the existing buildings.”