Simpson says staff were also told they would be given forms to apply for their pay through the Insolvency Service, which meant it would be “paid by the public purse”.
“I’ve been representing bar workers for over a decade and it is the worst mass redundancy I have dealt with, including during the pandemic,” he added.
Staff were told of the closures and cuts by Brewdog chief executive James Taylor on Monday.
The announcement came after Tilray bought the company’s UK brewing operations, brand, and 11 pubs. The deal saw 733 staff being transferred over to the new owners.
But 38 bars across the UK which were not included in the sale immediately closed with the loss of 484 jobs.
One member of staff who was made redundant at the meeting contacted the BBC to describe what has happened.
He wrote: “Because of the way they’ve handled it (by declaring administration and appointing AlixPartners to process that) they’ve managed to wash their hands of all those they made redundant yesterday.
“They have not paid any of us that worked over the weekend. For salaried staff none of the overtime we worked during February has been paid. Accrued holiday has been written off.
“We were told that we have to deal with AlixPartners if we want to get back into our stores to collect any personal belongings, and we’ve been told not to share our issues, stories, or concerns with anyone outside of AlixPartners.”
Brewdog has been contacted for comment.