I couldn't put a monetary value on it but in terms of scholarship it is extremely valuable

Dr Rachel Cowgill, Leeds University music department

"I opened the score and looked at the title page where it quite clearly said by Wolfgang Amadeus Mozart, then I realised it was Judas Maccabaeus," she said.

Mozart adapted four pieces written by Handel in the 1780s to make them more suitable to contemporary tastes.

Excitement

Although scholars have found references to an adaptation of a fifth piece, until now no trace of the work was ever found.

This news comes in the same week as an announcement by the Royal Academy of Music in London that it had found and authenticated a previously unknown Handel work.

As such it will send further ripples of excitement through music circles.

"It tells us much more about how Mozart responded to an earlier great master like Handel," said Dr Cowgill.

"I couldn't put a monetary value on it but in terms of scholarship it is extremely valuable."

Dr Cowgill is researching the library of William Priestly, a collector of German music and early member of Halifax Choral Society.

Priestly may have got the manuscript through his connection with a church in Fulneck, West Yorkshire, where a clergyman had bought several scores from a music publishers in Leipzig in 1817.

Mozart mastered his first piece of music in 30 minutes at the age of five

It is thought that Priestly presented the manuscript to Halifax Choral Society in 1850, and although they still own the piece, it is part of a collection that is on permanent loan to the record office.

Genuine?

The manuscript is not written in Mozart's own hand, but Dr Cowgill is convinced that the score is genuine.

"The things that he does in this arrangement match the techniques he used in his adaptation of Handel's Messiah," said Dr Cowgill, an expert on the composer.

Experts are examining the manuscript to decide whether it is genuine, something which can take some time. The authentication of the Royal Academy of Music's Handel discovery is thought to have taken years.

But Dr Cowgill feels that the evidence that this is indeed an unknown Mozart arrangement of Handel's oratorio is very persuasive.

She is planning to edit the arrangement and is discussing a possible performance with Halifax Choral Society.

Judas Maccabaeus will be better known to some as the source of the hymn Thine Be The Glory, written by Handel in 1747.

Handel was born in 1685 in Halle, Germany but spent many years in London where he was the Royal Family's favourite composer.

Mozart was born in Salzburg, Austria in 1756, while Handel died in 1759.