Workers at hundreds of Crown Post Offices are to strike on Easter Saturday in a dispute over closures, jobs and pay.
Members of the Communication Workers’ Union will walk out for 24 hours after backing industrial action by almost 9-1.
The union said up to 4,000 workers will be involved, at 373 Crown offices – the larger sites usually situated in high streets.
The action is in protest at plans to close or franchise more than 70 Crown offices, as well as over pay and jobs. Picket lines will be mounted outside the offices, which handle around a fifth of Post Office business.
A number of Crown offices have already been franchised to firms such as WH Smith.
The union said Post Office staff have not received a pay rise since April 2011.
The Post Office said it was “disappointed” with the strike, adding that the CWU refused to understand the requirement for “critical change” across the Crown network which is losing £40m a year.