Workers at hundreds of Crown Post Offices nationwide – including Matlock – went on strike on Easter Saturday in a dispute over feared closures, jobs and pay.
Members of the Communication Workers’ Union walked out for 24 hours after backing industrial action by almost 9-1.
The action is in protest at plans to close or franchise more than 70 Crown offices, as well as over pay and jobs.
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.
A Post Office spokesman said: “Crown branches are losing £40m and must be brought into profit. This is public money and a position which cannot be sustained.
“The Post Office is working hard by modernising and by winning new business to bring the Crown branches into profit by April 2015.
“We want to keep our branches and believe the best way is for 70 to seek out suitable retail partners.”