Plastic windows and doors are the biggest threat to the condition of England’s conservation areas, an English Heritage study reveals.

Plastic windows and doors were found to affect 83% of council conservation areas surveyed – the top item listed on the organisation’s annual Heritage at Risk register published on June 23.

The figure is twice as high as unsightly satellite dishes and loss of front garden walls, fences and hedges.

English Heritage is so concerned at the findings that it is launching a Conservation Areas at Risk campaign to get residents, groups and councils to improve the areas before it is too late.

“We want councils to make more use of Article 4 Directions (only 13% of conservation areas currently have one) to protect small but important original details such as windows, doors and front gardens,” said English Heritage chief executive Dr Simon Thurley.

An English Heritage poll shows 82% of estate agents think original features like timber sash windows add value to a property.