DEVELOPMENT rules in a historic market town are to be tightened to clamp down on modern building design.

The move aims to preserve the architectural features in Helmsley and is part of a new study of the town's conservation areas by the North York Moors National Park Authority and Ryedale District Council.

The study states: "The use of non-traditional building materials, such as plastic doors and windows, undermines the integrity of the historic fabric of Helmsley and has a very negative impact on the character of the conservation area."

The report, currently a consultation document, calls for legal restrictions to be imposed to curtail development rights of house and property owners.

Planning permission would be needed to replace windows and doors, alter chimneys, roofs or boundary fences.

In addition, says the report, there would be controls on rendering and painting stonework of cottages.