NATIONAL Gallery workers hailed their “highest turnout ever” yesterday as they began an all-out strike against job outsourcing.

Staff have for months been resisting plans to move 400 of their 600-strong team at the Trafalgar Square, central London, gallery into the private sector.

They were boosted yesterday by messages of solidarity from Labour leadership contender Jeremy Corbyn and an international trade union.

Mr Corbyn said workers had been forced to take action by the “intransigence of management.

“These low-paid workers are proud public servants and don’t want their jobs sold off.”

As new director Gabriele Finaldi takes over the gallery, Securitas has been named as the preferred bidder for the staffing contract.

The dispute has been worsened by the victimisation of Candy Udwin, a rep for staff union PCS, whose unfair dismissal appeal is expected to reach a conclusion in the next few days.

“The management of the National Gallery must reinstate Candy Udwin and call off plans to privatise the staff who look after our cultural assets,” said Mr Corbyn.

“I urge the incoming director Gabriele Finaldi to meet with the union and resolve this dispute.”

Workers have taken over fifty days of strike action this year in day and week-long stints, but they have now pledged not to return until management gives ground.

PCS culture sector president Clara Paillard told the Star that managers were panicking in response to the strike and had brought forward their deadline for transferring staff to Securitas from December to November.

“Securitas have been in the gallery (on Tuesday) seeking to meet individual members of staff, but they have been unsuccessful because of the strike,” said Ms Paillard.

She said there was “still uncertainty” over whether the contract with Securitas had been signed, but that PCS would continue to resist the outsourcing plans regardless.

“We are not going away whatever happens.”

Global union confederation Public Services International general secretary Rosa Pavanelli has visited the pickets in Trafalgar Square.