A group of protesters, including cleaners from the Barbican arts centre, stormed into the central London venue demanding the London Living Wage (LLW) last Saturday.
The City of London Corporation which runs the centre agreed to pay cleaners at the LLW in 2013. But it has yet to include the latest increase to £9.15 an hour introduced last November.
An HR rep from Mitie, the company that employs the cleaners, threatened workers who took part with dismissal.
Demonstrators played drums, horns and vuvuzelas, and waved banners in the main area in front of stunned visitors.