A mildewing box of tapes uncovered at a BBC radio station contained lost episodes of long-running Radio 4 series, The Archers.
The tapes were recorded in the Queen's Silver Jubilee Year, 1977
The recordings from 1977 will help fill gaps in the BBC's archives.
Six years ago the pile of tapes - containing 20 omnibus editions - was given to BBC Radio Wiltshire by a listener who had cleared her house.
The recordings survived thanks to Dr Barbara Carter, who taped the broadcasts for her elderly mother.
"I did this for her when she wasn't available. She never liked to miss an episode," she said.
The tapes had been left in a corner of the radio station and were almost thrown out last week.
But a member of the BBC's staff who is also an Archers fan, played the tapes and realised how old and rare they were.
Now it is hoped the tapes can be added to the programme's archive at the BBC in Birmingham, where The Archers is recorded.