Over the weekend, 21 caravans and 25 vehicles pitched up, illegally, inside the historic brewery and prevented staff from entering the site, leading to a stand-off with Lancashire Police and the group departing on Monday 28 May.
A spokesperson from the brewery said the group invaded the site, damaging vehicles and using offices as toilets and leaving a “disgusting mess” at the brewery, which was founded in 1807.
According to owners, 1,700 pints have been poured down the drain in case of contamination.
In a statement from Lancashire Constabulary, Supt Andrea Barrow commented: “On Saturday evening a large group of travellers entered the premises of Thwaites Brewery on Penny Street, Blackburn.
"Following on-going discussions with the travellers, they eventually moved on yesterday (Monday, May 28) afternoon.
“When faced with incidents such as these Lancashire Constabulary considers all options available, which included working closely with brewery management to resolve the situation.
"In this case we negotiated with the travellers to encourage them to move which they eventually did. We are aware that over the weekend there was a significant amount of damage caused and thefts which we are currently investigating. We are continuing to work closely with the brewery and local partners and will seek to prosecute those involved in this mindless criminality.
"I would urge anyone with information in relation to this incident to ring Lancashire Constabulary on 101 or contact independent charity Crimestoppers anonymously on 0800 555 111 or online at crimestoppers-uk.org."
In response to regaining control of their head offices and the travellers moving on, a spokesman for Thwaites commented: “We could not have achieved this without the help of Lancashire Police and the support of our local MPs.
“We would like to thank them for all of their assistance over a bank holiday weekend, which we appreciate is a busy time for them.
“It’s been an incredibly difficult and frustrating weekend for us all and we are now assessing the criminal damage that has been caused both inside and outside the building, which is considerable and what theft has occurred from the site.
“But despite it being a horrendous situation, we have also seen some fantastic work from our staff who have dropped everything to help or got on with their jobs in far from ideal circumstances.
“Thank you to everyone who has supported us, either in person or through messages. We really appreciate it and we are glad to have our site back.
“Our next task is to start a massive clean-up and get our business up and running once again.”