Aramark employees contracted to work the government's Department for Business, Energy and Industrial Strategy (BEIS) will stage an indefinite walkout next week after months of strike action at the site.
The action against the Irish foodservice operator signals a stark escalation of the employee group's dispute over pay, which began more than nine months ago and followed the acquisition of the contract from BaxterStorey.
Speaking to The Caterer, staff have complained of limited chances to progress in the firm, and that senior management is yet to meet with strikers. While staff had been assured their pay would be mapped to the median average for their role in London, striking workers claimed they were yet to see any change to their pay packet.
PCS general secretary Mark Serwotka said: "These workers have led a courageous campaign to win pay justice from unscrupulous and greedy contractors.
"For them to have no other choice but to take indefinite strike action is a testament to their dogged determination to win.
"PCS is supporting them all the way in their fight for the London Living Wage and I call upon the entire trades union movement to get behind our members.
"I urge BEIS to take control of this situation, put pressure on the contractors to pay up and ultimately bring all of these staff back in-house."
The action has gained support from several Labour MPs and figures in the trade union movement, including shadow business secretary Rebecca Long-Bailey, shadow chancellor John McDonnell and TUC chair Frances O'Grady.
A spokesperson for BEIS said: "We value all of our staff at BEIS and our priority is to ensure they receive a fair wage for their hard work, whether directly employed or working for our contractors.
"This is why we ensured that our contractors aligned the pay of cleaning, catering, mail room and security staff to the median rates for those occupations as identified in the 2018 Annual Survey of Hours and Earnings."
Aramark did not respond to The Caterer‘s request for comment.