Six Extinction Rebellion protesters on trial for blockading the printing press of some of the UK’s biggest newspapers have been found guilty.

The activists appeared at St Albans magistrates court on Friday accused of obstructing the highway outside Newsprinters printing works in Broxbourne, Hertfordshire, on 4 September 2020.

Judge Sally Fudge convicted the defendants, saying that while the demonstration was “peaceful” it had a significant impact on the ability of businesses to function and caused newspapers to lose an estimated GBP1m.

Extinction Rebellion (XR) said it was considering an appeal and that “history will decide where the real guilt lies”.

The court heard that about 50 XR members used vehicles and bamboo structures to deny access to and from the Broxbourne site.

The Newsprinters presses publish the Rupert Murdoch-owned News Corp’s titles including the Sun, Times, Sun on Sunday and Sunday Times, as well as the Daily Telegraph and Sunday Telegraph, the Daily Mail and Mail on Sunday, and the London Evening Standard.

The Crown Prosecution Service decided to try six defendants at a time.

This is the second trial related to the printing press blockade. A 12-month conditional discharge was given to defendants Caspar Hughes, 49, of Exeter; Elise Yarde, 32, of Walthamstow; Amir Jones, 39, of London; Charlotte Kirin, 51, of Bury St Edmunds; and Hazel Stenson, 56, of Bury St Edmunds. They were also ordered to pay GBP150 court costs plus GBP22 victim surcharge.

Laura Frandsen, 30, of London, received a GBP150 fine and GBP150 court costs plus GBP34 victim surcharge.

Fudge concluded the police had acted proportionately in arresting the protesters, adding: “The level of disruption caused by the protest was high, and the obstruction of the highway went on for a very long time … In my view the protesters had, up until the point of arrest, been able to exercise their article 10 and 11 rights with little, if any, interference from the state, and that part of the protest had already had some impact on Newsprinters’ ability to conduct its business in the usual way.”

During the trial, the court heard how the home secretary, Priti Patel, had made multiple calls to commanding officers about the protest and requested to “expedite” their removal.

Raj Chada, defending, said an independent review of the incident, commissioned by Hertfordshire constabulary, found officers had been placed under “significant political pressure”.

However, Fudge said she found police had “maintained their operational independence” and Patel’s conversations with senior officers had not influenced decisions taken on the ground.

Sentencing the defendants, Fudge said: “This was a peaceful protest with no suggestion of damage caused by anybody and no abuse or obstruction of officers. You all spoke in your defence with passion and clarity and it was obvious that you had thought carefully about what you were doing.”

Afterwards, XR said: “History will decide where the real guilt lies. As floods devastate Europe, another heat dome is building in the United States, and environmental defenders across the world are being silenced, XR will continue to demand that the press tell the truth about the climate and ecological emergency.

“The media is a central pillar in helping the public understand the scale of the response needed. Our captive press is failing in its democratic responsibility. We are considering our options for an appeal.”

A verdict was expected last month but Fudge agreed to postpone the trial to await the outcome of a supreme court judgment, which on 25 June overturned the convictions of four protesters who had locked themselves together outside an arms fair in 2017.

The four demonstrators were found to have been exercising their rights to free speech and assembly and had a lawful excuse.