Campaigners against large scale quarrying at a beauty spot near St Keverne have won the first stage of their campaign with a High Court victory on Friday.

The Community Against Dean Superquarry (CADS) received an early Christmas present after a High Court judge ruled that Cornwall Council should have demanded an Environmental Impact Assessment (EIA) before granting permission to quarry owner Shire Oak Quarries.

The announcement, which follows a judicial review on November 13, means the company's initial planning application has been deemed unlawful and planning permission will now be quashed.

Silke Roskilly, the claimant for CADS, said: "I am delighted with the judgment made by The Hon. Mr Justice Dove. He has confirmed our concerns that the planning department of Cornwall Council did not follow correct procedure when they granted planning permission to reopen Dean Quarry earlier this year.

"The Planning Officer recommended to the Planning Committee that permission should be granted despite knowing that CADS had asked The Secretary of State for a screening direction. At no point did the Planning Officer ask the developer Shire Oak Quarries Limited for an Environmental Impact Assessment (EIA), when in fact the development needed one and thus EIA regulations were broken."

A CADS spokesperson added: "The fight is far from over but for now Cornwall Council and the developer have received a serious blow."

Campaigners first became concerned about the reopening of the quarry last autumn after it was announced as one of the possible supply sites for stone for a new tidal energy lagoon in Swansea Bay, with plans to massively upscale production from the levels at which it was run prior to closure in 2005.

Although Shire Oak Quarries said the site would provide up to 50 local jobs, campaigners were not convinced, and also worried about the impact of increased traffic through St Keverne and the potential damage to tourism: They felt around the clock operation could create noise and light pollution at the site, which sits in an Area of Outstanding Natural Beauty (AONB) on the coastal path.

Campaigners are also concerned about the damage a proposed jetty and 500 metre breakwater would have on a newly created Marine Conservation Zone (MCZ) at the Manacles.

In April, Cornwall Council granted planning permission for a perimeter fence, fuel and explosive storage, and office, reception and amenity areas at the site, in what Walter Sanger, Cornwall Councillor for St Keverne, described as a “salami sliced” application - a precursor to an application for the jetty and breakwater, which has yet to be submitted.

But Greg Clark, Secretary of State for Communities and Local Government, overturned the decision, due to the lack of an EIA, opening the door for the High Court appeal.

A spokesperson for Cornwall Council said: "The council notes the judgement and will be discussing options with its legal advisors."

Shire Oak Quarries has said that it has not been chosen as the provider of stone for the Swansea Bay tidal lagoon project, as the Chinese contractor working on the project has yet to make a decision, and the outcome of that process will affect rock production and transportation plans at the quarry.

A spokesman for the company, whose chief executive Mark Shorrock also runs Tidal Lagoon Power, the company behind the Swansea Bay project, said: “We are disappointed with the judgement and now await the Council’s next steps in relation to determining our application for ancillary works. Dean Quarry has a valid minerals consent to operate until August 2035 and that consent is unaffected by today’s decision.”

The decision means Cornwall Council will have to pay the majority of Mrs Roskilly's costs.