A POLICE force may have to preserve its distinctive radio mast even when it becomes obsolete.

The 150ft-high concrete tower at Durham Constabulary's headquarters at Aykley Heads, Durham City, could be declared a listed building.

But the force, like others across the country, is moving to a new digital radio communications system that will probably make the mast redundant. If it is listed, the force will not be able to knock it down and will have to pay for its continued upkeep.

The tower, designed by Ove Arup and Partners was chosen by English Heritage as a structure that should be listed because of its "elegant, ultra-thin design" and the way it meets high construction standards yet is sensitive to the surrounding area.

The final decision on whether the tower is listed will be made by Minister for Culture Tessa Jowell.

"As a radio mast it is unique, you can't deny that," a force spokesman said.

"But if it is officially listed we could not alter it or demolish it and would be responsible for its upkeep. Like any concrete structure it has a fixed lifespan and we would need to find out what it is."