Cinema workers who won a pay rise after a series of strikes yesterday announced that they may be forced to walk out again after bosses backtracked on the deal.

Ushers at the Ritzy cinema in Brixton were told when they reached a settlement with management that their pay would be backdated to the new rate. But they found that contrary to their agreement, bonus payments had been deducted from back payments.

Last night a source close to the dispute told the Star that the cinema had deployed a manager who is a notorious union buster to deal with further negotiations. Workers are represented by entertainment union Bectu.

“What’s happened is they’ve calculated the bonus as pay — in our gross pay — whereas we always rejected the notion that bonuses are any sort of pay,” the source said.

“Because even if you look at the definition of what the bonus is, it’s something that is given on top. So we’re challenging that.”

A communication to supporters of the Ritzy workers said the union was “officially disputing the misleading way in which the company have treated their commitment to paying us backpay to October 2013.

“Please be aware that this could result in industrial action,” the memo continues.

Ritzy workers had initially campaigned to be paid the London Living Wage of £8.80 an hour, but settled last month for what amounted to a 26 per cent pay rise over three years.

Workers received support from filmmakers including Ken Loach and Mike Leigh.