According to BBC News, the painted cloth backdrop was used for what was reportedly the first professional British performance of Verdi's Macbeth, staged by Caspar Neher. It will be added to the archive collection housed at the Glyndebourne country house.
Glyndebourne's executive chairman, Gus Christie, told the BBC, "I was amazed to find this piece of Glyndebourne's history in relatively good condition. The backcloth would have been painted by hand and it is remarkable how the colors have remained so vivid.
"The piece gives us a snapshot of what this production must have been like when it was first shown to audiences almost 70 years ago."
The 2007 Glyndebourne Festival Opera runs from May 19 to August 26; the lineup includes a new Verdi Macbeth, the company's third.