Jim Reeves, from the Communication Workers' Union, says the argument to close 70 Crown Post Offices is flawed because the business is profitable.
He spoke to ITV News Central outside the Kings Heath branch in Birmingham as staff went of strike this morning.
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An ecstatic bus driver went to work the day after winning £6.1 million on the lottery as "people rely on him for their morning commute".
Rain across the far north may become persistent and heavy at times through the day.
Rain will spread across northern parts from the east this afternoon. Dry in the south.