A fourth defendant has been convicted of conspiring to embark on a wrecking spree after a 100-strong group of Travellers illegally occupied a brewery.
On Thursday, Patrick Ward, 32, from Leigh, was found guilty in his absence at Preston Crown Court of conspiracy to burgle and commit damage at Thwaites Brewery in Blackburn, Lancashire.
A convoy of more than 25 vehicles - including 17 caravans - entered the town centre site after one of the gang used a chainsaw to cut a lock on a pedestrian gate and then opened the main gates on the evening of May 26.
The trial heard how gang leader Thomas Ward, 43, demanded cash to leave and said to brewery bosses: "Twenty grand or the place is ours."
But the Travellers caused an estimated £300,000 damage after Thomas Ward realised he was not going to get the money.
Staff and police finally gained full access to the brewery on May 28 and Thwaites chief executive Richard Bailey said he was greeted by a scene of "utter devastation".
The Travellers finally left later the same day under police escort, the court heard.
A warrant has been issued for the arrest of Patrick Ward after he failed to attend this week's hearing.
Raids took place on June 26 in Levershulme Park in Bolton where the Wards had set up camp, Lancashire Police said.
Key clothing, believed to have been worn during the destruction, was discovered.
During a search of Thomas Ward's caravan, around £1,700 cash was recovered along with two USB sticks labelled with "Daniel Thwaites PLC".
Speaking on Thursday, Superintendent Andrea Barrow from Blackburn Police said: "We promised we would seek justice for Thwaites, their staff and the public and following a thorough investigation we are extremely pleased with these convictions.
"When Thwaites's staff entered their place of work they were met with scenes of utter devastation. Not only had lots of equipment and alcohol been stolen, the power had been cut, windows had been smashed, office furniture damaged, food had been thrown over floors and a water cooler had been tipped over causing flooding.
"Employees' personal possessions had literally been scattered around and 1,700 pints of beer had to be thrown away.
"It was extremely upsetting for the staff who had had been due to end over 200 years of brewing at this particular site around 12 weeks later. However, they had to make the tough decision to not brew there again, such was the risk of contamination.
"The behaviour of all the people involved in the damage and destruction was utterly deplorable. Thomas Ward not only had the audacity to force employees off company property, he then tried to coerce them into paying thousands of pounds for the Travellers to leave. Thankfully no money was handed over in spite of his demands."
Discussing the investigation, she added: "Lots of work went on behind the scenes to ensure we traced the right people, arrested them and gathered enough evidence to secure convictions. The conspiracy charges demonstrate the seriousness of the offences that were committed.
"I would like to thank Thwaites, who we have been in regular contact with throughout the investigation and court process.
"I would also like to remind people the level of destruction and damage caused to the site is not reflective of the behaviour of all Travellers. These were criminals who behaved in a completely unacceptable manner and they have been dealt with as such.
"We know other people were involved who haven't yet appeared before the courts and so our investigation continues to ensure we trace them and bring them to justice also. If you know anything that could help, please get in touch."
Chief executive officer at Thwaites, Richard Bailey, said: "We were shocked and horrified by this unprovoked and criminal attack on our business back in May, and wish it had never happened.
"We take some comfort from the steps taken by the police to apprehend some of those responsible, and the fact that these men pleaded guilty speaks for itself. We have now moved to Thwaites's new brewery and wish to put the whole matter behind us."
On Monday, Thomas Ward, of Aspull Common, Leigh, pleaded guilty to blackmail, conspiracy to burgle Thwaites and conspiracy to commit criminal damage.
John Ward, 33, of Aspull Common, and a 17-year-old male, who cannot be named for legal reasons, also admitted the conspiracy offences.
Prosecutors said Patrick Ward, also of Aspull Common, was among offenders caught on CCTV stealing items at the brewery.
Jurors were told Patrick Ward denied it was him.
The three adult defendants will be sentenced on January 11.