The unfinished Liszt opera — written largely in shorthand, with only one act completed — languished in a Weimar archive for nearly 170 years. David Trippett, a senior lecturer in music at the University of Cambridge who discovered it there a decade ago, has spent the last two years working on the 111-page manuscript. A 10-minute scene will be performed by the soprano Anush Hovhannisyan at the BBC Cardiff Singer of the World competition this summer.

“It is music born of great ambition, and it sounds like that,” Mr. Trippett wrote in an email, saying that he heard in it elements from Liszt’s Petrarch Sonnets and glimmers of Wagner. “Peeling back the layers when I was deciphering the manuscript was slow work, but I was always sustained by being able to hear the sounds in my head and play through the emerging score at the piano.”