Villagers in Collyweston are irritated that the local planning authority has authorised the use of blue Spanish slate on two homes in their village – the source of one of the country’s most famous stone roofing tiles.

But it is not the fact that Collyweston stone is not being used that concerns them – they wouldn’t mind mock stone concrete tiles being used – it is the colour they object to because it will contrast with the genuine stone tiles on the roofs of many of the buildings in the village.

The builder, GP Construction of Langtoft, had originally proposed using mock Collyweston concrete but East Northamptonshire District Council has made it a condition of planning approval that the slate is used.

The Council’s Senior Conservation Officer, Lloyd Mills, says: “National guidance advises that we should not be employing artificial building products in historic areas and instead we should be using natural, traditional materials, as is the case here.

“While natural Collyweston stone would be the most appropriate roof covering in this area, there are very limited supplies of this material and these should be retained for the repair of historic buildings.”

The Council had originally rejected the planning application for the two houses because they said the houses were visually obtrusive with an unacceptable overbearing impact on nearby houses. That decision was successfully appealed against.

Collyweston Parish Council Chair, Shelagh Busby, said: “We see this example as a change of policy, from use of an artificial roofing material that looks very like Collyweston slate, to use of a so-called ‘natural’ material that looks completely wrong in this setting.

“The district council’s response shows the planners have no idea about the consequences of this decision for the future protection of the conservation area. We’re concerned that it sets a precedent for the future which will erode the design features that make Collyweston so special.”