Cornwall Council has said it will not appeal after losing a High Court judgement over plans to develop Dean Quarry near St Keverne.

The council has decided not to challenge the judgement, which overturned its decision to grant planning permission to quarry owners Shire Oak, and said it will "take a pragmatic view" about the costs of arguing what it calls "a point of principle."

An appeal was launched by Silke Roskilly on behalf of campaign group Cornwall Against Dean Superquarry (CADS), and in December the Honourable Mr Justice Dove ruled against the council, calling its decision to grant planning permission "unlawful."

Plans for several buildings and a perimeter fence at the site were granted permission in April last year after deciding the work did not require an Environmental Impact Assessment (EIA), and without awaiting the outcome of a screening direction from the Secretary of State for Communities and Local Government, which had been requested by CADS.

In his ruling, Mr Justice Dove said: "If the planning authority chooses to grant consent and prior to the resolution of a direction requested of the Secretary of State then they run the risk that if that direction is positive they will have granted planning consent which is infected with illegality."

He added: "No reasonable planning authority, knowing at the time when they formed a resolution to grant planning permission that there was an outstanding request of the Secretary of State... would proceed to grant planning permission without knowing the outcome."

The judge was also highly critical of the council for not thinking the development, in an Area of Outstanding Natural Beauty and a Site of Special Scientific Interest, and bordering a Marine Conservation Zone, could have significant environmental effects or merit an EIA.

Cornwall Council, which will have to pay the majority of Mrs Roskilly's costs, said the judgement had "serious implications" for the council and other local planning authorities "as it could change the way that both applicants and those opposing development will operate."

It said the judgement assumes that the council will be aware of all relevant requests to the Secretary of State which "in practice, will not be the case."

It said: "The judgement further centralises planning powers as it appears to permit a request to the Secretary of State for a decision on whether or not an Environmental Impact Assessment is required after planning permission has already been granted by the local planning authority.

"This may have the practical effect of requiring local planning authorities to await the Secretary of State’s decision as to whether an EIA is required before granting planning permission. This could have the effect of rendering uncertain a previously lawfully made screening opinion unless confirmed by the Secretary of State or sufficient time has passed since the issuing of the planning permission."

A spokesperson for Shire Oak said: "We have been informed of the council’s decision not to appeal the judgement and will now take some time to consider our next steps."