Elizabeth Bain, who runs a sub-post office in the Scottish Highland hamlet of Tore, near Inverness, took her case to an industrial tribunal last month after working out she was being paid just pounds 2.22 an hour for a 37.5- hour week.
She has won the right to a full hearing which, if successful, could cause an avalanche of similar claims from the Post Office's 17,500 sub-postmasters across Britain demanding the legal minimum of pounds 3.60 an hour.
Mrs Bain, 52, who has been running the garden-shed sized sub-post office in Tore for 23 years, said: "I am very, very pleased. I think it should help a lot of people in my position - I hope it will anyway.
Mrs Bain said the next stage involved producing evidence of how many hours she had worked and how much she had received for it. "That isn't difficult - I can just show my wage slips," she said.
The Post Office had argued unsuccessfully that Mrs Bain was an "agent", not a worker, and so the National Minimum Wages Act 1998 did not apply.
Mrs Bain's lawyer, Victor Tough, said: "She didn't do it for the money. She's not like that. She just felt morally it was unfair. We felt the Post Office had taken a stance which was both contractually and morally wrong," he said.
Mr Tough said Mrs Bain would be entitled to back-pay from April of this year, when the National Minimum Wages Act 1998 came into force.
A spokesman for the Post Office said an appeal was being considered.Reuse content