A forgotten Vaughan Williams score will have its world premiere on Thursday.
A Cambridge Mass, written when the composer was a student at Trinity College, Cambridge, had been filed away in the University Library.
Conductor Alan Tongue discovered the piece in 2007 and spent the past year transcribing it.
Vaughan Williams was just 26 when he wrote the mass, but Mr Tongue said: "Every bar already had the hallmark of a great composer."
The choral manuscript was submitted for his Doctor of Music examination in October 1899.
It lay undiscovered until the university held an exhibition of some of its 500,000 volumes of printed and manuscript music scores.
Mr Tongue said he was amazed when he stumbled across the unknown work.
"There was a big sheet of Vaughan Williams - a work that I had clearly never seen before, and it looked so good I wanted to hear it," he said.
"It had been mentioned in a few books but no one had ever bothered to take it out and try to perform it, which is extraordinary. It's waited for 110 years."
Vaughan Williams's 45-minute work for four soloists, double chorus, orchestra and organ was given the title A Cambridge Mass by Mr Tongue. The composer had originally named only the individual movements.
"It's very significant and is the earliest large-scale Vaughan Williams work that we have," said Mr Tongue.
"And it's a very positive, carefree, happy, optimistic piece composed just before his famous hymn-writing period and very unlike his later bleak period."
Mr Tongue will conduct the first performance of A Cambridge Mass at Fairfield Halls in Croydon.
"As a conductor I take a lot of English music around the world and normally I'm introducing foreign audiences to the work of Elgar, Vaughan Williams, Holst and so on.
"This time I shall be introducing a work of Vaughan Williams to a British audience and that will give me a lot of pleasure," he said.
"It's not a student work at all. But let's see what the reviewers and musical experts think of it."