Greenpeace has been cleared of environmental breaches after dropping boulders on the seabed in a celebrity-backed operation to protect marine life, with a judge saying prosecution was not in the public interest.

The Marine Management Organisation (MMO) started proceedings against the campaign group – and its chief executive, John Sauven – after it put in place anti-trawling measures in the English Channel.

The Offshore Brighton area, 28 miles off the coast, was designated a Marine Conservation Zone, with its coarse sands and gravel hosting a diverse range of species.

Greenpeace dropped 20 granite boulders in the area, despite warnings from the MMO that it was not licensed to do so, in February 2021 because it felt the area needed protecting from trawlers.

Celebrities including Thandie Newton, Hugh Fearnley-Whittingstall, Paloma Faith, Bella Ramsey, Mark Rylance, Jarvis Cocker and Ranulph Fiennes backed the campaign and had their names on boulders.

The MMO announced it was bringing a prosecution against Greenpeace and began proceedings at Newcastle Crown Court – close to its headquarters in the city – with a five-day jury trial scheduled for June.

But at a hearing last month, Judge Edward Bindloss invited the MMO to reconsider, saying prosecution was not in the public interest.

He said: “One of the ironies of this litigation is that both the MMO and Greenpeace are committed to improving the marine environment.”

He added: “The parties in this case should be allies, not antagonists. They should be acting in harmony given their stated purpose and objectives are the same.

“Greenpeace should be a supporter of the licensing regime and the MMO should support the prevention of any harmful deep sea fishing methods over important marine seabeds.

“It touches on the absurd that this litigation is happening at all.”

Judge Bindloss said deciding not to prosecute Greenpeace was not “favouritism by the MMO towards a well-known organisation” and the move would not set a precedent.

He said the boulders were not harmful to the marine environment and Greenpeace’s actions were not dangerous.

The judge said Greenpeace had given advance warnings of the operation and had marked the co-ordinates of each boulder, which had holes in so they could be lifted back off the seabed later.

The MMO considered its position and offered no evidence after Greenpeace and Mr Sauven pleaded not guilty to charges of undertaking marine activity without a licence.

Kirsty Brimelow QC, for Greenpeace, told a hearing at Newcastle Crown Court on Monday: “On behalf of Greenpeace, there is an acknowledgment that common sense has prevailed by the MMO and a welcoming of that common sense so that all can work to protect the marine environment.”

Our action was designed to safely protect nature from destructive fishing in an area designated as protected but where the MMO is miserably failing to do its job. For them to waste court time and public money prosecuting us for doing exactly that is, as the judge said, absurd

Outside court, Mr Sauven, who has now stepped down as executive director at Greenpeace UK, said: “Our action was designed to safely protect nature from destructive fishing in an area designated as protected but where the MMO is miserably failing to do its job.

“For them to waste court time and public money prosecuting us for doing exactly that is, as the judge said, absurd.

“This is a clear signal for the environment minister to take the urgent action needed to actively protect our oceans from industrial fishing, and stop licensing destructive ships and fishing methods in all of the UK’s Marine Protected Areas.”

Each side will pay its own costs.

The MMO said it expects Greenpeace to comply with marine licensing rules in the future.

A spokesman said: “Should unlicensed activity occur in the future, we will continue to investigate and will consider enforcement actions in line with our published compliance and enforcement strategy.”