A controversial cull of seagulls to lower the risk of bird strike to aircraft has been blocked by the Court of Appeal.
The killing of 552 pairs of lesser black-backed gulls in Lancashire was sanctioned by former environment secretary Owen Paterson at the request of aerospace company BAE Systems.
Further operations were also authorised to maintain the population at a reduced level, provided it did not fall lower than 3,348 pairs, and to continue operations to control the number of herring gulls following an earlier cull. Words: PA.
BAE Systems requested the culls to reduce the risk of bird strike to aircraft operating at the company's Warton aerodrome (pictured) in the Ribble Estuary.
The High Court last year dismissed claims by the Royal Society for the Protection of Birds (RSPB) that the cull was unlawful and would set a dangerous precedent.
But three appeal judges have unanimously overturned the High Court and ruled Mr Paterson's decision, made in May 2013, was "fatally flawed" and quashed it.
The RSPB said it feared killing the birds would lead to bird culls elsewhere.
The charity said it accepted the risk to aircraft but questioned the legality of the Government sanctioning the killing of birds without acknowledging the damaging impact of removing "almost a fifth of the breeding population of a species on a protected site".
The society added the case set "a deeply disturbing precedent for our most important sites for wildlife".
High Court judge Mr Justice Mitting ruled the RSPB legal claims "unfounded" in May last year and dismissed an application for judicial review and ordered the society to pay £10,000 in legal costs.
But Lord Justice Sullivan and two other appeal judges have now declared the single judge went wrong in law.
Lord Justice Sullivlan said the birds affected nested in an extensive area of sand and mud flats and saltmarsh on the south bank of the Ribble.
It was classified as a special protection area (SPA) under the EU Directive on the Conservation of Wild Birds.
But Mr Paterson had "misinterpreted the conservation objectives of the SPA".
The judge ruled the minister had considered the level of the cull on the "erroneous premise" that the number of birds left would remain favourable for breeding and conservation purposes, and the cull would not adversely affect the integrity of the site.
The judge said: "For these reasons, the secretary of state's decision to direct Natural England to give consent for the cull is fatally flawed.
"I would allow the RSPB's appeal and quash the secretary of state's decision dated May 29 2013."
Lord Justice Jackson and Lord Justice Sales agreed that the appeal should be allowed.