An unperformed choral work composed by Ralph Vaughan Williams more than 100 years ago will be premiered next year.
The 45-minute piece, called A Cambridge Mass, was discovered during an exhibition at the Cambridge University Library.
Conductor Alan Tongue, who found the piece, said: "I knew immediately that here was a significant work."
Mr Tongue will conduct the concert, which will take place in March.
The score, written for soloists, double chorus and orchestra, was composed when Vaughan Williams was aged 26.
He wrote it in 1899 for his Doctor of Music examination at Cambridge University and still has pencil markings made by the examiners.
It has been kept in storage at the library's manuscripts room and up until now had been overlooked.
An excerpt of the work being played at Vaughan Williams' Cambridge college, Trinity, has been made available on the university's YouTube site.
After Mr Tongue's discovery he obtained a copy of the original score and spent last year transcribing it to make a modern performing edition.
"It soon became clear that no performance had ever taken place as there were too many uncorrected mistakes," he said.
"As my computer played the synthesised sounds, just imagine, I was privileged to be the first person to hear the work."