The leader of a 100-strong group of travellers who illegally occupied a brewery told its bosses: "Twenty grand or the place is ours," a court has heard.
A convoy of more than 25 vehicles - including 17 caravans - entered Thwaites Brewery in Blackburn 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.
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 from 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.
Ward has 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 oftravellers 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 thetravellers, 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, hours after Thwaites had been allowed in - with police assistance - to remove a number of valuable items, including artwork and memorabilia worth £2 million, in a horsebox and a beer dray, a number of males were seen to trespass the office building from about 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 Morrison's supermarket and Gala Bingo on May 27.
The trial continues.