The leader of a group of travellers attempted to blackmail a brewery boss for £20,000 before ordering a 100-strong gang to destroy the building when demands were not met, a court was told.
A convoy of more than 25 vehicles - including 17 caravans - entered Thwaites Brewery in Blackburn after one of the group used a chainsaw to cut a lock on a pedestrian entrance and then opened the main gates on the evening of May 26.
A spokesman for the travellers allegedly told brewery bosses: "Twenty grand or the place is ours".
Thomas Ward, 43, of Aspull Common, Leigh, Greater Manchester, initially demanded £20,000 from Thwaites to leave within the hour before he settled on a handshake to take payment at noon the following day provided no damage was caused, jurors at Preston Court were told.
But prosecutors say travellers went on a wrecking spree and ransacked the office building later that afternoon after Ward formed the view his demand would not be met.
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", with extensive damage estimated at £300,000.
The travellers finally left later the same day under police escort, the court heard.
With a brewing heritage that stretches back over 200 years, Thwaites sells its beer exclusively in its chain of pubs, hotels, inns and lodges.
In 2001, Prince Charles toasted Thwaites Beers at Craven Heifer, Stainforth and in 2005 the company signed cricketer Andrew Flintoff to become the face of their ‘Lancaster bomber’ as he helped England win the Ashes.
On Tuesday, Ward pleaded guilty to blackmail, conspiracy to burgle Thwaites and conspiracy to commit criminal damage.
John Ward, 33, also of Aspull Common, and a 17-year-old male, who cannot be named for legal reasons, also admitted the conspiracy offences.
A fourth defendant, Patrick Ward, 32, of Aspull Common, who has pleaded not guilty to the same conspiracy offences, is on trial at Preston Crown Court in his absence.
Jurors heard that a security guard on duty at Thwaites rang management to say they had a "major problem" after the travellers broke in.
In a statement to the court, Mr Bailey said when he arrived he saw a large number of travellers and vehicles in the yard.
Dog kennels had already been laid out in what was clearly an "advanced stage of encampment".
Work contractor Greg Hartley had already discussed with "Big John", a spokesman for the travellers, his terms for them leaving, said Mr Bailey.
Mr Hartley said: "Big John said give me 20 grand and we'll be gone in the next hour."
He said he relayed the message to Mr Bailey and explained to Big John it was not possible to obtain any money immediately.
They finally agreed on a handshake for a noon handover as Big John reminded him: "Twenty grand or the place is ours," he continued.
On May 27, Thwaites were allowed into the premises - with police assistance - to remove a number of valuable items, including artwork and memorabilia worth £2 million.
A number of males were seen to trespass the office building in a horsebox and a beer dray, at around 4:30pm.
The CCTV - which also showed young children playing in the yard - stopped recording when the power was cut on site at about 5.50pm, the court heard.
Kimberley Obrusik, prosecuting, said it was the Crown's case that Patrick Ward was one of the offenders caught on CCTV stealing items at the brewery.
Jurors were told that Patrick Ward denies it was him, although he does accept he was in the area at nearby Morrisons supermarket and Gala Bingo on May 27.
The trial continues.